Tesar Sebatyne, a Jedi Knight of the Barabel species, received training from his mother, Saba Sebatyne. He also served as a pilot in the Wild Knights, their squadron comprised of individuals strong in the Force.
Due to Barabel reproductive practices, Tesar shared a father with either Bela Hara or Krasov Hara. Determining which one was his true sister proved impossible. Nonetheless, all three emerged from the same clutch and shared a deep, sibling-like connection.
Following the Battle of Duro, Tesar, along with his clutchmates and the Jedi Izal Waz, aided Han Solo and Leia Organa Solo in evading assassins dispatched from Corellia, while also protecting their master Eelysa.
Two years into the conflict, Tesar, his clutchmates, and the Wild Knights made their presence known in the war. During the skirmish at Froz, Tesar, Bela, and Krasov impressed their fellow Jedi with their remarkable coordination and tactical prowess through the battle meld.
When the danger posed by the voxyn became evident to the Wild Knights after Master Eelysa's passing, Tesar volunteered for the strike team sent to Myrkr, becoming one of the few to survive. Tragically, both of his clutchmates perished during the mission.
After a brief period on Hapes following the events on Myrkr and the fall of Coruscant to the Yuuzhan Vong, Tesar rejoined the Wild Knights. He fought valiantly at Borleias during the campaign under the leadership of General Wedge Antilles.
As the war progressed into its third year, Tesar was formally promoted to the rank of Jedi Knight in a ceremony held on Mon Calamari. He then served under the command of Admiral Traest Kre'fey as a flight leader in Jaina Solo's Twin Suns Squadron. During the Battle of Ebaq 9, Tesar, Jaina, and Lowbacca found themselves trapped inside a bunker on the moon's surface. He was rendered unable to fight during the confrontation with Warmaster Tsavong Lah.
For the remainder of the war, Tesar alternated his service between the Twin Suns Squadron and the Wild Knights. He piloted a Zonama Sekotan fighter during the Battle of Yuuzhan'tar at the conclusion of the Yuuzhan Vong War.
In 35 ABY, Tesar, Lowbacca, and Jaina Solo apprehended the Yaka pirate Redstar aboard his vessel, the Night Lady. They later attended his trial at the high-security space station MaxSec Eight. During the trial, they received a mysterious Force-based summons from the Unknown Regions. Joining the other survivors of the Myrkr strike team, they embarked on a journey to discover the source of the call, eventually finding that it originated from Raynar Thul, their former Jedi comrade who was believed to have died on Myrkr, but had been transformed into the Prime Unu of the hive-minded Killik species.
Tesar, along with Tekli, Alema Rar, Jaina Solo, Zekk, Lowbacca, and Tahiri Veila, was manipulated into joining the Killiks through UnuThul's use of the Myrkr battle meld. He became a "Joiner," someone influenced and controlled by the Colony, subjected to Force and pheromonal manipulation that profoundly altered brain structure. The Joiners then aided the Killiks in defending their nests against the Chiss. However, Luke Skywalker eventually convinced Tesar to return to known space. Following the Qoribu Truce, Tesar and Lowbacca began hunting pirates who were hijacking Abaarian water shipments.
Similar to how Jaina and Zekk developed a dyad within the Joiner meld, Tesar seemed to form a particularly strong bond with Lowbacca and Tahiri. In the final months of the Killik conflict, the three conspired to reveal Raynar's survival to Aryn Dro Thul, his influential mother. Tesar and Lowbacca were the ones who informed Madame Thul about the New Jedi Order's potential plans to assassinate her son, as Raynar, in his UnuThul form, was believed to be either intentionally or unintentionally causing the Dark Nest to repeatedly reappear.
When Luke Skywalker discovered their actions, he considered them a betrayal of their loyalty to the Jedi Order, as they had undermined his efforts to unite the Knights as Grand Master. Tesar and his friends attempted to redeem themselves by informing Luke about Jacen Solo's attack on Supply Depot Thrago, but their efforts were in vain. Luke sent them to Dagobah to contemplate the true meaning of being a Jedi. He instructed them to remain there until he felt they were ready to rejoin the order, and not to leave until they received his summons.
By 40 ABY, Tesar and Lowbacca were serving under the command of Admiral Nek Bwua'tu. Their specific mission was to monitor the clandestine Kiris shipyards. Tesar was among the many Jedi Knights who attended the Funeral of Mara Jade Skywalker, where his mother delivered the eulogy. Sebatyne later participated in a massive battle meld during the Second Battle of Balmorra.
Near the conclusion of the Second Galactic Civil War, Tesar sparred with fellow Jedi Lowbacca and Zekk against Jaina Solo, in preparation for her upcoming confrontation with Darth Caedus, formerly known as Jacen Solo before his descent to the dark side of the Force. Tesar was also involved as Jaina learned to harness the power of shatterpoints. The war ended after Caedus's death, following his defeat at Jaina's hands.
In 43 ABY, Tesar, alongside fellow Barabels Wilyem, Zal, and Dordi, assisted in removing the mentally unstable Jedi from Coruscant and transporting them to the Jedi facility on Shedu Maad, after Chief of State Natasi Daala sought to freeze them all in Carbonite. They later established a nest within the Jedi Temple.
When Grand Master Luke Skywalker instructed the Jedi Order to evacuate Coruscant as a strategic trap for the Sith, he tasked the four Barabels (Tesar, Wilyem, Zal, and Dordi) with hunting down and eliminating any Sith they encountered.
When Allana Solo experienced a vision of Sith attacking and killing the Hatchlings, she and her grandparents, Han and Leia Solo, returned to Coruscant to inform Jedi Knight Bazel Warv so he could alert the Barabels to the impending assault. However, they were ambushed at the secret exit of the Jedi Temple, led by Vestara Khai. Jedi Warv made the ultimate sacrifice, defending the House of Solo from the Sith, thus becoming a hero for Allana Solo.
When the Parting Gift arrived to rescue the group, along with numerous Hatchlings, Tesar Sebatyne revealed that his baby Barabels had taken a liking to Jagged Fel.
Tesar attended the Wedding of Jagged Fel and Jaina Solo and likely participated in the tradition of Jedi igniting their lightsabers to create an arch for Jaina Solo Fel to walk under.
He, along with his mother Saba Sebatyne, the Hatchlings, and his nestmates Wilyem, Zal, and Dordi, departed Coruscant and relocated to Shedu Maad.