Tierny

The human female Tierny lived during the reign of the New Republic. For some time, she scraped her way through life to survive and eventually joined the First Order, having believed she was meant for a bigger purpose. Eventually, she became an agent in the secretive First Order Security Bureau by the time of the conflict between the First Order and the Resistance. During her service, Tierny became known for her aggressive and manipulative interrogation tactics, sometimes lulling her targets into a false sense of security. In 34 ABY, the First Order occupied the supertanker fuel depot Colossus on the Mid Rim planet Castilon. While there, Commander Pyre led his garrison's stormtroopers to arrest Team Fireball upon the revelation that the crew's namesake racer had been used by Resistance members trespassing in the First Order–controlled Sector Epsilon 51-3 in the Unknown Regions' Dassal system. Although the mechanics Jarek Yeager, Kazuda Xiono, and Neeku Vozo escaped, one of the team's members, the mechanic Tamara Ryvora, was captured. Tierny was sent to the Colossus to interrogate Ryvora and root out any Resistance presence, and Pyre prepared for the agent's arrival.

After landing her shuttle, Tierny was met by Pyre and the Colossuss Captain Imanuel Doza, and they traveled to Doza's office in Doza Tower. When Ryvora was brought into the office by stormtroopers, Tierny immediately approached her in a friendly and comforting fashion, ordering the mechanic's binders removed. When Doza began interfering in the agent's questioning of Ryvora, the First Order agent escorted the confused mechanic to the Aces' Lounge, where they could converse privately. During the conversation, Tierny attempted to positively frame the First Order's quest for galactic peace by using her well-honed guile to manipulate Ryvora's feelings toward her friends.

Afterward, the agent revealed to Ryvora that her colleague Xiono was not who he had claimed to be—he was actually a former New Republic Navy pilot and a member of one of the Core Worlds planet Hosnian Prime's wealthiest families who had been recruited into the Resistance. Having believed Xiono was from a poor background, Ryvora was shocked to learn more about his past when the agent gave her a datapad containing his service record. When the Colossuss alarms blared shortly afterward and the station began to shake, Tierny left the lounge to investigate, placing Ryvora under two stormtroopers' guard.

The agent returned to Doza's office, demanding that the captain inform her of what was happening. Doza, who had secretly been collaborating with Team Fireball members Yeager and Xiono to sink the Colossus to sabotage the First Order's communications blackout and contact the Resistance by accessing the transmitter outside Doza Tower, lied and claimed that a reactor malfunction must have been occurring. At Pyre's directive, Doza began closing the Colossuss emergency hatches to prevent the station from flooding. The trio watched from Doza's office as the refueling station slowly sank into Castilon's seas, leaving only Doza Tower above water.

Tierny then conversed with Pyre, with both agreeing that the timing of the alleged reactor failure was suspicious, given that Resistance spies were still running loose on the Colossus. After a man informed Tierny and Pyre via comlink that the First Order's jamming signal was not operational, Doza suggested water damage as a probable cause. However, Tierny looked out the window and noticed that the transmitter was above the water line, causing Pyre to leave to deal with the situation. Although Xiono and his astromech droid CB-23 escaped after contacting the Resistance, Yeager was captured by stormtroopers while stalling so the pair could flee.

Seeing Ryvora as a potential asset to the First Order, the agent decided to recruit her to their side by presenting herself as a kind and understanding alternative to her former colleagues. Tierny treated Ryvora to a sumptuous meal in the Aces' Lounge, telling her she deserved more than the Colossus had to offer. The agent further sought to sully Ryvora's opinions of Xiono and Yeager, expounding on their connections to the Resistance with recorded evidence of their actions. When Ryvora responded that Yeager was only trying to protect Xiono by pretending to be a spy, Tierny countered that the recording showed both were Resistance operatives and that she could not trust the former because he had kept secrets from her.

The mechanic was troubled by the agent's claim, at first disbelieving the evidence provided but eventually coming to see the agent as a guide and interpreting her evidence as compelling. Shortly afterward, Tierny escorted Ryvora through a corridor on the Colossus, and they encountered a captive Yeager as they passed by. Despite Yeager warning the mechanic that the First Order was manipulating her, the agent convinced Ryvora to continue following her to Doza Tower. Tierny stoked the mechanic's resentment toward Xiono by suggesting that he was deceptive. Aware of Ryvora's desire to become a pilot, Tierny offered her a place with the First Order by claiming they could train her to reach her potential.

When Xiono and his colleagues—Team Colossus—flooded the Colossus as part of a plot to expel First Order forces, Tierny and Pyre were present in Doza Tower. Upon a stormtrooper informing them that they had lost five more troopers, Tierny advised Pyre to bring reinforcements and told him that she was taking Ryvora offworld. Not wanting to lose control of the station, Pyre advocated for a "more aggressive solution" if the station could not be raised but also agreed on taking the mechanic off the platform. After the First Order officers left Doza's office, Yeager—who had been secretly listening to their conversation while hiding in the room with Doza—resolved to not let Ryvora leave the Colossus. At Doza Tower's landing platform, Tierny and Pyre accompanied Ryvora aboard a waiting Upsilon-class command shuttle.

While there, Xiono and Yeager tried to convince Ryvora not to leave with the First Order, but she was still bitter towards them for keeping secrets from her and felt he had made her false promises as a cover for his Resistance operations. Exploiting the conflict between Ryvora, Xiono, and Yeager, Tierny claimed that the First Order was giving Ryvora protection and a new purpose. As the Colossus fired up its hyperdrive to flee Castilon, CB-23 squirted oil, causing four stormtroopers at the top of Doza Tower to fall onto the landing platform. Meanwhile, Xiono and Yeager eliminated the other nearby stormtroopers. Tierny and Pyre engaged in a firefight with Xiono while waiting for their transport to arrive, and then they evacuated Ryvora from the platform alongside a stormtrooper. As the Colossus rocketed into space, the First Order dispatched Major Elrik Vonreg's squadron and a Resurgent-class Star Destroyer to destroy the Colossus. However, the station escaped into hyperspace.

After boarding the First Order Resurgent-class Star Destroyer Thunderer, Pyre and Tierny reported to Captain Phasma on the Colossuss whereabouts, assuring her that the refueling station would soon be in the First Order's grasp. Despite Tierny's confidence in their success, Phasma indicated to the pair that if they could not control the station, then they should destroy it, or she would personally see to their execution. After the conversation, Ryvora was brought to meet with Tierny and Pyre, with the latter indicating that they were eager to hear any information she had to share about her former colleagues. The mechanic told the First Order operatives what she knew of Xiono and Yeager's association with the Resistance but eventually insisted she had told them everything she was aware of. After promising her loyalty to the First Order and agreeing to help hunt down the Colossus, Ryvora was made a First Order cadet by Pyre and Tierny. Although they dismissed the cadet—now given the callsign DT-533—to acquire her uniform, Tierny continued to doubt Ryvora's loyalty.

When Ryvora received a message from Xiono on her personal comlink, she turned the device over to Tierny and Pyre to show her loyalty to the First Order after being persuaded to do so by fellow recruited cadet and former Colossus resident Jace Rucklin. The agent was pleased with the cadet's volunteering of information, giving the comlink to Pyre to use. The First Order traced the comlink's signal to the former Resistance planet D'Qar, which had been the site of a recent battle between the First Order and the main Resistance fleet. Tierny deduced that the Colossus crew were unaware of what had transpired and traveled to the location to rendezvous with the rest of the Resistance. Aboard the Thunderer, she traveled to the world to find the Colossus stranded amongst the debris over D'Qar, unable to make the jump to hyperspace, as the crew had initially planned to refuel at the Resistance base.

With no other options, Xiono led a team to salvage hyperfuel from the ruined Mandator IV-class Siege Dreadnought Fulminatrix. The Thunderer arrived while the Resistance cell was still aboard the wreckage, and Tierny launched an attack on the Colossus; thanks to intelligence provided by an officer, her forces opened fire on what remained of the First Order Star Dreadnought. Doza deployed the Aces to counter the offensive, aiming to protect both his space station and Xiono's team amidst their coaxium extraction effort. Tierny watched the space battle from the Thunderers bridge, eventually witnessing a heavily damaged Colossus jump to hyperspace once Xiono's team returned to the station with the needed coaxium fuel. The agent asked Ryvora if she would continue to inform them of any future attempts to contact her by her former colleagues, to which the latter agreed. Although Pyre felt that the cadet should be firmly conditioned to ensure her loyalty to the First Order, Tierny disagreed, believing that Ryvora's state at the time would better help them find the Colossus. The agent later stored the cadet's comlink in her office aboard the Thunderer.

Not long afterward, Tierny devised a plot to capture the Colossus in its damaged state. She hired the engineer Nenavakasa Nalor to track the refueling station in her ship and board the station under the guise of helping them with repairs while secretly sabotaging the station. After accepting Tierny's offer of employment, Nalor traced the Colossuss path for a few days, eventually faking a distress signal that prompted Xiono and his colleague Synara San to bring her aboard the refueling station. Nalor sabotaged the station's systems using a k-spline component, broadcasted its location to the First Order, and reported back to Pyre so that he credited her account with payment for the endeavor while fleeing.

Despite his initial doubts, Pyre was impressed that the agent's plan seemingly succeeded as the Thunderer arrived at the Colossuss location. However, Xiono and Vozo worked swiftly to reverse Nalor's damage to the station and successfully evacuated the Colossus from the area after getting its systems back online. When the commander pointed out that Nalor had failed to sabotage the station entirely, Tierny indicated that the First Order should execute the engineer if the First Order ever found her again.

While still hunting for the Colossus, Tierny traveled aboard the Thunderer after tracking the station's signal beacon to a location in space. The supertanker fuel depot fled after First Order forces began attacking, but a lone Resistance pilot—Venisa Doza, who had been attempting to rendezvous with the Colossus—entered the area from hyperspace, flying in her X-wing with her astromech droid, Torch. After Doza was caught in the Thunderers tractor beam, she was brought to the vessel's hangar and met Tierny, who asked about her identity. When the pilot refused to volunteer information, the agent ordered her to be taken into custody and her ship's logs to be inspected for clues.

A stormtrooper informed Tierny shortly afterward that the ship and Torch both appeared fried. Although stormtroopers tossed Torch into a junk pile, assuming the droid to be non-operable, the droid whirred back to life and rescued Doza from her cell. The Resistance pilot took Ryvora hostage while heading to the Thunderers Bay 2, attempting to convince her to defect from the First Order by revealing her own identity as a member of the Doza family and a friend of Yeager. Doza stunned the young cadet when she refused, and Tierny entered the hangar behind a contingent of troopers. After Torch used explosives to set a TIE fighter aflame, the agent realized the incident was a diversion providing cover for Doza's escape and ordered the area to be locked down.

The agent then indicated to nearby stormtroopers that they should shoot down a TIE fighter taking off from the hangar, assuming the Resistance pilot was inside. However, Torch was piloting the craft as another diversion, letting the ship slowly get fired upon while his pilot boarded her starfighter. As Tierny and the other First Order forces watched, Torch ejected from the damaged TIE and reconnected with Doza's vessel as it jumped into hyperspace. Shortly following the incident, Tierny asked to meet with Ryvora and verified that the cadet had been held captive by Doza during her escape. However, Ryvora lied to the agent, claiming that the pilot had not revealed her identity. While Tierny was skeptical of Ryvora's answers, she simply told the cadet to comply with her security debriefing.

The Colossus—still fleeing from the First Order—desperately needed a trans-binary deflector replacement; failing to retrieve one would lead to the deaths of all on the station due to cosmic radiation. After Xiono and Vozo stole one from the First Order supertanker fuel depot Titan, Pyre informed Tierny via hologram that the two Colossus residents had stolen the part from the Titan. When the agent inquired if Ryvora had contacted her former colleagues, the commander indicated that she had not. Tierny considered the information, eventually reflecting that the new cadet would be the key to locating the Colossus.

After receiving a Resistance distress signal from the Outer Rim planet Varkana, Xiono, Yeager, San, and CB-23 investigated the world while the Colossus remained in its star system. However, the group soon became trapped in the bounty hunter Ax Tagrin's ship alongside the Resistance spy who had originally sent the distress signal—the Duros Norath Kev—whom Tagrin had captured earlier. After Tagrin informed Pyre of the Resistance group's capture aboard his ship, the commander and Tierny traveled aboard the Thunderer to Varkana and took a transport to land on Varkana. While Xiono and Kev escaped the bounty hunter's custody, San, Yeager, and CB-23 were recaptured and escorted into the Vargo Spaceport's main hangar to meet with Tierny and Pyre upon their arrival.

Tierny coldly addressed Yeager by name, lamenting that their past meetings had been too brief for them to get acquainted, and she led him and San aboard a First Order shuttle with the help of two stormtroopers. While still docked in the hangar, the agent interrogated the pair using electric shocks in interrogation chairs, probing for the location of the Colossus. When Yeager pleaded for her to stop harming San, she mocked him for his compassion for the pirate and confronted him for his treatment of Ryvora by keeping secrets from her. She then turned her attention on Yeager fully, electrocuting him as she repeatedly implored him to tell her his method of contacting Resistance General Leia Organa and where else the Resistance was hiding throughout the galaxy. Although the mechanic insisted he did not know the information she was looking for, Tierny replied that he was lying, noting that Ryvora had told her about his past as a member of the Rebel Alliance.

Although the pair briefly argued over whether the First Order was manipulating the young cadet, Tierny was called away to help with an issue at console A2 and remarked that she would finish her interrogation later. When San noted that the agent would not stop until she had her answers, the pair began considering ways of escaping. Tierny, who was helping Pyre and another stormtrooper crack the memory banks of CB-23 from a console, watched as First Order Lieutenant Galek reported to Pyre that the Colossus had just left the Varkana system. As the agent looked on, CB-23 was then electrocuted by a tech stormtrooper in an attempt to get her to reveal the station's location. When that trooper succeeded in accessing the droid's main databanks, Tierny ordered them to drain all the information they could from CB-23 and destroy her afterward.

After Tierny left the consoles, CB-23 knocked the stormtrooper unconscious and hooked into the system, frying the nearby equipment. The agent noticed the power shorting out as she walked away, and she headed back toward the area with her blasters drawn. However, CB-23 swung down from the ceiling and knocked the agent out, leaving Tierny groaning on the floor. After Xiono and Kev freed San and Yeager, CB-23 rejoined the group, which fled Varkana aboard a shuttle and eventually returned to the Colossus and escaped to hyperspace.

Having been fleeing from the First Order for months, the Colossus eventually attempted to settle on the Outer Rim planet Aeos Prime permanently. However, the First Order tracked them to the world with a probe droid's report, which contained an image of Xiono in the Fireball leaving Aeos Prime. Tierny pointed out the Resistance spy's identity to Galek and Pyre, having been informed of the development by a First Order bridge lieutenant. When the agent mentioned the world's population had once worked with the Rebel Alliance, Pyre declared that they should have wiped out the Aeosians in the past and ordered a course set for the Aeos system. Upon arrival, the Thunderer began attacking the Colossus as it attempted to flee to hyperspace. Tierny watched the battle progress from the Thunderer, listening as Pyre directed their Star Destroyer to fire on the refueling station's engines to take out their hyperdrive. Tierny was surprised when Ace Squadron attacked their much larger vessel head-on, considering the move foolish.

While flying in Yeager's ship, Xiono attempted an attack run on the Thunderers bridge, firing a missile when in range. However, Ryvora's TIE fighter blocked the projectile while Tierny and Pyre watched, with the officers ducking to brace for impact in the moments prior. The Colossus continued to ascend into Aeos Prime's orbit and jumped to hyperspace as the agent looked on from the bridge. She remarked to Pyre that General Armitage Hux would not be pleased, though he replied that the general was not who he was concerned about. Afterward, Tierny and Galek visited Ryvora and congratulated her on her performance in the skirmish, promoting her to second squadron commander.

Not long after, aboard the Thunderer, Tierny and Pyre briefed Galek and three First Order cadets on recent reports of Resistance activity near the Outer Rim planet Dantooine, with Pyre ordering their vessel to set course for the world since the TIE squadron patrolling that area had fallen out of contact. As the Thunderer jumped to hyperspace, Tierny continued surveying a holographic projection of Dantooine. Later, the agent asked Ryvora to meet with her in her office aboard the Star Destroyer and inquired how she was. As she fiddled with Ryvora's comlink—which the cadet had turned over to her previously—in her hands, the cadet eyed the device while insisting she was doing great due to her promotion as second squadron commander. Tierny admitted her past doubts about her but noted she was wise not to have been deceived by her former colleague Xiono.

As the agent tucked the comlink into her desk's drawer, Ryvora took note of where she placed it. Tierny expounded on her life before the First Order to the young woman, explaining that she had brought the mechanic to join them because of her potential. The agent insisted that Ryvora must continue to surpass her expectations but eventually dismissed the cadet when Galek called for all squadrons to prepare for launch. Upon arriving at Dantooine, the Thunderer engaged a contingent of Resistance escorts and Ace Squadron pilots protecting three shuttles of Resistance recruits. Although Rucklin destroyed one of the shuttles in the ensuing dogfight, Galek was killed in the skirmish, and the rest of the combatants escaped. Tierny later met with Ryvora and consoled her over the mission's failure and Galek's loss. The agent then promoted her to squadron commander for the successful destruction of one of the three shuttles during the endeavor under her command, noting that Galek's failure created the opportunity for her promotion. Despite Tierny's praise, Ryvora was troubled by the conflict between her moral compass and duties as part of the First Order.

Following the Dantooine endeavor, Tierny traveled to the Aeos system aboard the Thunderer. In retaliation for having served as a sanctuary for the Colossus, she and Pyre oversaw the suppression of the Aeos system with thirteen other Resurgent-class Star Destroyers, bombarding the planet and killing the Aeosians that had helped the Resistance. The pair then contacted Admiral Hux via hologram from Tierny's office and reported the attack's completion. However, Supreme Leader Kylo Ren took Hux's place in the terminal's feed and berated both Tierny and Pyre for failing to find the Colossus. Although Tierny attempted to appease the Supreme Leader, he did not accept her excuses and threatened to replace both officers if they could not complete their assigned objective; Ren used the Force to make them both draw their blasters and aim them at each other, only letting them go after several moments. The impatient Supreme Leader warned them that he would not tolerate further failures, giving them only one more chance to find the Colossus.

Tierny and Pyre exited the office, resolved to double their efforts. Moments after their departure, Ryvora used the reprogrammed MSE-6 series repair droid 5-L to sneak into the agent's office and take her comlink from the room's desk. After conversing with an officer to request a report, Tierny returned to her office as the cadet attempted to hide from her. The agent was distracted by 5-L's presence, allowing Ryvora to slip from the room as her superior asked the droid whether it had completed the system upgrade. 5-L beeped at Tierny and hurried from the room, attracting her gaze as she left the room too and shut the door.

Ryvora sent a message in a mechanic's code to Xiono and Vozo, asking them to help her escape the First Order by meeting her on Castilon. Afterward, she changed the hangar bay launch location of her upcoming TIE fighter training station to a different hangar bay on the Thunderer. Tierny met with the cadet and Rucklin as she prepared her ship, questioning why she had altered the location of her session. When Ryvora claimed that Operations must have moved it, Tierny ordered Rucklin to assist her, letting the pair go while watching them intensely. The pilots then went to the Tashtor sector—where Castilon was located—for their training session.

A First Order officer aboard the Thunderer informed Tierny and Pyre that sensors had indicated Ryvora's squadron had jumped to Castilon. The agent and commander shared a glance, with the latter commenting that the new squadron leader must have felt homesick. Tierny then left and went to her office, finding Ryvora's comlink missing from her desk, as she had stolen it earlier. The agent was disappointed with the betrayal—having thought she gave Ryvora both training and purpose in life—and figured out the rest of the lieutenant's plan to defect. With this knowledge, the Thunderer traveled to Castilon to intercept the squadron leader. Eventually, the vessel captured her and those who had come to her aid—Xiono, Yeager, and CB-23—and Rucklin, catching their shuttle in a tractor beam. Tierny confronted Ryvora for her treachery, lamenting that she had had great potential. Although the agent expounded that the punishment for treason was death, the recruit claimed she was no longer afraid of her.

Rucklin then revealed that the Colossus was in the Mid Rim's Barabesh system to Tierny and Pyre but was nonetheless led away from the scene by stormtroopers despite his claims of innocence. Xiono and Yeager, hiding in the hangar bay with the shuttle, ran away from the vessel as stormtroopers searched it. One stormtrooper ran out of the captured ship, indicating to Tierny that it was set to self-destruct. She then ordered nearby troopers to fall back but was not quick enough to escape the blast and was tossed to the floor. Alarms blared as Tierny shakily rose from the floor; she pulled out her blasters and began shooting at Xiono and Yeager. She directed the stormtroopers with her not to let them escape as she chased after the pair.

As the agent continued exchanging blaster fire with the Resistance combatants, Pyre ordered the Thunderers command to travel to the Barabesh system. The commander eventually joined her, chasing Xiono and Yeager out of the hangar and behind a blast door as both sides shot at each other. After seeing them disappear behind the door, Tierny called an individual working for the Thunderers security and told them to issue a Code Red due to the Resistance agents loose on the vessel. They agreed to lock down all positions, responding affirmatively. Pyre informed Tierny that the Thunderer was on its way to the Barabesh system to confront the Colossus, leaving nowhere for the station to hide. She retorted that they may both face the consequences if he was not right, stalking away from him.

On the Thunderers bridge, a stormtrooper informed Tierny and Pyre that Ryvora had escaped and joined Xiono and Yeager as they fled from First Order forces and were last seen in turbolift G-27. Meanwhile, the fugitives snuck to the engineering section of the Star Destroyer and transmitted a message to the Colossus, warning their colleagues that the First Order was on its way. Pyre and his stormtroopers captured the group shortly afterward and brought them to face Tierny on the Thunderers bridge. She commended the trio for their tenacity but stated the First Order would stamp out their resistance shortly. The agent then questioned Ryvora as to her reason for betraying the First Order. The mechanic firmly replied that Yeager had given her a family, which Tierny found distasteful.

Moments later, the Thunderer arrived in the Barabesh system close to the Colossus, much to the horror of the captured trio on the bridge, who had hoped the refueling station had fled due to their sent warning. As Pyre ordered the First Order to attack, Tierny mocked that the group could now watch their "family" perish from the Star Destroyer's bridge. A bridge lieutenant informed the agent and the commander that Colossus pilots were attacking their thrusters, to which the former insisted that their shields could not be breached. At Tierny's directive, Pyre left the bridge to prepare a boarding party.

Working in secret, CB-23 deactivated the Thunderers deflector shields, and an officer on the bridge relayed the news to Tierny. She demanded that they be brought back online, but the lieutenant insisted that they could not. When a blast from an enemy combatant rocked the bridge, Tierny and her troopers stumbled to catch their balance. Yeager, Xiono, and Ryvora used their momentary distraction to take out the troopers, shoot at the agent, destroy the bridge's controls, and flee the Thunderer. Tierny raised her blaster and moved to pursue them, but they made it safely behind a door before she could.

While still on the bridge, Ren contacted Tierny via hologram, with the latter insisting she had the Colossus within her grasp but needed reinforcements. The furious Supreme Leader berated the agent for her failure, did not accept her excuses, and choked her. Tierny struggled to breathe, grasping at her collar, until Ren eventually killed her using the Force. Ace Squadron then fired at the Thunderers engines for the final time, causing the machinery to explode and cause a chain reaction—which killed all on board. Not long after, in 35 ABY, the Resistance defeated the First Order and Sith Eternal cult's forces at the Battle of Exegol.

Tierny had brown eyes, dark skin, and a scar on her jaw. She kept her black hair in a complex knotted updo to maintain her curls. Having struggled to survive during the time of the New Republic, Tierny hoped to restore peace to the galaxy through absolute order. The intimidating agent was a staunch believer in ruling with an iron fist, having little mercy for those who disagreed with the goals of the First Order and considering it her main priority to root out all forms of opposition with laser-like precision. She felt treason to her organization was one of the worst crimes and was willing to order the execution of those who failed in their duties. Though Tierny maintained a collection of blasters in her office's display cases, she otherwise held no interest in art. Pyre and Tierny shared a workable affinity despite occasionally being skeptical of each other's methods.

The agent viewed Ryvora as having great potential and saw a lot of herself reflected in the mechanic, wanting her to rise in the First Order's ranks and put her skills to use. By presenting herself as a sharp contrast to Pyre's aggressive stormtroopers, the agent used her persuasion skills to sow a wedge between Ryvora and her colleagues Yeager and Xiono, claiming that they had withheld information from her because they did not trust her. With Ryvora troubled by the news, Tierny succeeded in manipulating her into joining the First Order and becoming a cadet—while also willingly giving up information on her former colleagues—including turning her comlink over to her and Pyre.

The agent continued being invested in the cadet's progress within the First Order and was proud when she performed well in skirmishes, issuing her both of her promotions—first to second squadron commander and later to squadron commander after Galek's death. She made an effort to ensure her protégé was doing well, taking time to meet with her in her office. Meanwhile, the agent expressed sharp derision for Ryvora's former father figure, Yeager, and how she felt he had treated the mechanic. Tierny expressed a sense of betrayal when Ryvora defected from the First Order, not understanding the mechanic's attachment to her "family" from the Colossus. She enjoyed exacting revenge on enemies of the First Order, pleased at the concept of making Yeager, Ryvora, and Xiono watch the Thunderer destroy the Colossus in the Barabesh system.

As a specially trained weapons expert and intelligence agent, Tierny had access to information on enemies of the First Order, including Xiono and Yeager's backgrounds. The agent was a master manipulator, preferring to lure her targets into a false sense of security. She prided herself on her methods and was able to quickly shift between an icy demeanor and a caring facade. Although she did not often resort to aggressive tactics, the formidable First Order agent engaged combatively with Resistance agents, including when she tortured Yeager and San on Varkana during an interrogation. During her First Order service, Tierny proved capable of wielding twin blasters against enemy combatants.

As an agent of the First Order Security Bureau, Tierny wore a uniform designed by herself due to having no standard uniform. She donned a ribbed, long-sleeved gray undersuit that featured extra knee padding and the inscription "FOSB" in the Aurebesh language. Over this, she wore a fitted black chest armor piece alongside black shoulder pauldrons featuring the First Order insignia in white. Tierny carried standard First Order–issued code cylinders on a gray-and-black utility belt, two black holsters holding two black RK-3 blasters, and a sharply angled black helmet with a facial opening. She also wore gray gloves with black paneling, tall black boots, and gray pants with knee openings over her undersuit.

When she was sent to the Colossus on Castilon, Tierny used an Upsilon-class command shuttle and had access to a datapad that was able to display holograms. As she and Pyre tracked the Colossus across the galaxy, they both held command over the Thunderer. For some time, Tierny also maintained possession of Ryvora's personal comlink when the cadet turned the device over to her and Pyre to help track the Colossus. While on Varkana, Tierny used two electric interrogation chairs to question Yeager and San.

Tierny's office aboard the Thunderer featured two transparent, illuminated cases displaying several of her weapons, which were mounted to two opposing walls. The collection included five bladed weapons, four rifles, and one blaster. The office's desk in the center of the room also featured storage compartments.

Tierny first appeared in "Descent," the nineteenth episode of the first season of the animated television series Star Wars Resistance, which aired on March 3, 2019. Prior to the episode's release, she appeared unidentified in a mid-season trailer released on January 9 of the same year.

Tierny was first identified by name in the StarWars.com article "Cosplay Command Center, Part 1: Dressing the Resistance for Star Wars Celebration Chicago," written by Kristin Baver after interviewing Star Wars Resistance art director Amy Beth Christenson. Christenson briefly explained the new character's background and gave cosplay ideas for her costume for the upcoming Celebration Chicago convention, noting that fans would have been properly introduced to the agent by the time of the event, which began on April 11, 2019. A card of a Xi-class light shuttle on Castilon—noted to be transporting Tierny—was included in the Hotshots and Aces II Reinforcements Pack for Atomic Mass Games' Star Wars: X-Wing Second Edition ship-to-ship combat game, which was released on November 25, 2022. However, Tierny uses other types of vessels during her arrival on Castilon and departure shortly afterward in Star Wars Resistance.

Tierny was voiced by Sumalee Montano, a voice actor who had previously worked on Star Wars Legends projects, including voicing the Force Adept Lashowe in the 2004 video game Star Wars: Knights of the Old Republic and portraying the Mandalorian Shae Vizla in the 2011 video game Star Wars: The Old Republic, as well as working on the current canon's 2019 video game Star Wars Jedi: Fallen Order as the Partisans lieutenant Mari Kosan. On August 14, 2019, Sumalee was announced to be reprising her role in the then-upcoming second season of Star Wars Resistance in a StarWars.com article for the season's trailer. The second season's first episode, "Into the Unknown," premiered on April 15, 2019, at Celebration Chicago, and later debuted on television on October 6, 2019.

In an interview, Montano noted that working on Star Wars Resistance meant a lot to her and that being involved in a franchise so universally loved made the experience unique, as each voice actor would be equally excited about the project. She felt that collaborating on the animated show as Tierny was notably different than her experiences working on Star Wars video games, as the cast often recorded together, and especially commended Mary Elizabeth McGlynn for her work as voice director and Xiono's actor Christopher Sean for binding the cast together as a team. Sean and Ace pilot Torra Doza's actor—Myrna Velasco—agreed with the sentiment, praising Montano's ability to change from a friendly demeanor to cold and manipulating while recording as Tierny with them. Montano especially appreciated the writers' work in developing Ryvora's story arc and Tierny's role in it, finding great happiness in that two women of color formed a relationship on screen, which added diversity and representation. The actor was stunned speechless the first time she saw Tierny in animated form during a recording session, much to the rest of the cast's amusement. Montano enjoyed Tierny's role as a villain in pushing Ryvora toward the First Order, having loved the inherent struggle between the light and dark sides of the Force as a fan.

Montano also felt that her character's deep belief that she was not evil made her a much better villain for the show and personally related to the agent's backstory, also enjoying how Tierny's name seemed to be a play on the word "tyranny." While working on Star Wars Resistance, she and Pyre's actor, Liam McIntyre, worked on developing their offscreen chemistry so that their portrayal as onscreen First Order rivals would be smoother. Montano's favorite Resistance scene was from the "The Escape" as Tierny and Pyre were forced to turn their blasters on each other, noting that she enjoyed recording it with McIntyre. Star Wars Resistances head writer Brandon Auman said that the conflict felt by Ryvora as she got sucked in by Tierny in "No Escape" was very emotional for him to watch, even years after the show's release.

Lucasfilm Animation artist Jason Pichon created a concept-art illustration of Tierny on September 27, 2017. Colas Gauthier—another Lucasfilm Animation artist—made a concept-art illustration of her blasters dated to the following day. For the season two episode "Rebuilding the Resistance," Gauthier completed two pieces of concept artwork for Tierny's office aboard the Thunderer and for the weapons displayed in the room's wall cases, both dated to September 20, 2018.

The agent's costume design was based on real-world riot police gear, such as those worn by the United States' SWAT teams, as well as Navy SEAL garments. Additionally, the training garments of Navy SEALs influenced the knee padding and ribbing of Tierny's military-style sweater. Her helmet's style was based off of ones worn by Sith Lord Darth Vader and Imperial Security Bureau Agent Alexsandr Kallus. Christenson theorized that Tierny's shoulder armor could have been repainted from parts of a First Order trooper's kit as part of the agent's customization of her uniform choices. The art director also felt that the agent's hairstyle was drawn simply, probably reflecting that she had a number of naturally lush locks. Tierny's office was designed to include a collection of weapons displayed in cases, which Christenson contrasted to the decorative art collection maintained by Grand Admiral Mitth'raw'nuruodo "Thrawn" as shown in the animated television series Star Wars Rebels.

The original outline of "Descent" did not include Tierny and instead had Pyre arresting and questioning Ryvora. By the first draft of the episode's script, Pyre was replaced by an "Admiral Tierny," and by the next script version, she had been redefined as a security agent from the First Order Security Bureau. The division was originally developed for the Star Wars: Poe Dameron comic-book series as the First Order's version of the Imperial Security Bureau. In the early development of the episode "Rebuilding the Resistance," the conversation between Ryvora and Tierny would have been the episode's opener as a teaser. However, by the final iteration of the episode, Venisa Doza's arrival at the Colossus is instead shown first to better set up the mission and plot.

In "The Escape: Part 1," Tierny realizes that Yeager and Xiono rigged their shuttle to explode and indicates to her troopers that the situation is a setup. The StarWars.com article "Bucket's List Extra: 5 Fun Facts from "The Escape - Part 1" - Star Wars Resistance" revealed that her reaction was intentionally worded to not copy the iconic Star Wars catchphrase "It's a trap!," which was introduced to the franchise in the 1983 original trilogy film Star Wars: Episode VI Return of the Jedi, said by Admiral Gial Ackbar. In the draft scripts sent to actors for auditions for Star Wars Resistance, Tierny's name was listed different from its final iteration, which her voice actor Montano suspected was done to hide her identity.