Sol Rivas, a human and a Lieutenant within the ranks of the First Order, found himself embroiled in a deadly situation during the Battle of Starkiller Base. He uncovered data on a computer system that revealed Captain Phasma's involvement in deactivating the superweapon's deflector shields. To conceal her transgression, Phasma attempted to eliminate Rivas. However, Rivas managed to escape in a TIE/fo space superiority fighter, eventually crash-landing on the rough, ocean-dominated planet of Luprora. There, he was taken prisoner by the primitive R'ora inhabitants and held within their stronghold. Phasma eventually located him and carried out his execution to safeguard her secret.
Before his service as a Lieutenant in the First Order military, Sol Rivas underwent training to become a pilot. He was stationed at Starkiller Base when the First Order-Resistance War began in 34 ABY. During the Battle of Starkiller Base, he accessed files related to the defense shield and discovered Captain Phasma's culpability in its deactivation. Phasma had been coerced into this action by Finn, Han Solo, and Chewbacca to preserve her own life. Following this, the Resistance members had disposed of her in a garbage compactor.
After her escape from the garbage chute, Phasma returned to the computer she used to lower Starkiller Base's shields and erased the records of her actions. Realizing that Rivas had also accessed the computer and possessed evidence of her betrayal, she attempted to capture Rivas and falsely accuse him of lowering the superweapon's shields and compromising its security. Locating Rivas on Level Two, Phasma tried to shoot Rivas, but ultimately failed due to the bombing runs of Resistance Forces. Rivas was able to escape to the surface with Phasma in hot pursuit. As the planet disintegrated around him, Rivas managed to reach an auxiliary hangar where he escaped aboard a TIE/fo space superiority fighter.
Driven to hunt down and kill Rivas in order to conceal her own wrongdoing, Captain Phasma, along with TIE fighter pilot TN-3465, and the BB unit BB-K8 pursued him in a TIE/sf space superiority fighter. However, they were unable to shoot him down because their fighter's laser cannons were not functioning. Running low on fuel, Rivas was forced to land his fighter on the harsh, water-covered planet of Luprora. Shortly after landing, he was captured by the indigenous R'ora, a semi-sentient species of red-skinned, bipedal creatures with tentacles. Rivas was imprisoned within the R'ora stronghold, which the Lupr'or, a humanoid colonizing species, considered to be impenetrable.
For a period of four days, Rivas was held captive by the R'ora. He was bound with ropes inside the R'ora's tower and suffered a bruised right eye and several scratches inflicted by his captors. Determined to locate and eliminate Rivas, Captain Phasma orchestrated an assault on the R'ora stronghold with the assistance of the Lupr'or. Phasma exploited the chaos of the battle to gain access to the tower, where she discovered a bound Rivas. Initially, he was relieved to see Phasma. However, Phasma informed him that she had come to execute him for his alleged treason.
Rivas responded with a defiant grin, feigning ignorance. Phasma demanded that he confess to his supposed guilt and clear his conscience. Rivas retorted that he had nothing to confess and pleaded with Phasma to spare his life in exchange for his silence. When Phasma repeated her demand, Rivas pointed out that she was the one who had deactivated the shields, leading to Starkiller Base's destruction. Desperate to avoid taking responsibility for her actions, Rivas promised that he would not reveal her secret. In response, Phasma fatally shot him with her blaster rifle.
Unbeknownst to Rivas, TN-3465 witnessed his execution, having disobeyed Phasma's orders to remain behind and guard the entrance. Before departing Luprora, Phasma destroyed BB-K8 and killed TN-3465 in an attempt to eliminate any remaining loose ends. Phasma then fabricated a report, claiming that she had tracked down and executed Rivas for his alleged role in Starkiller Base's destruction.
Sol Rivas was a human individual with blond hair and blue eyes. He bore a scar around his left eye and cheek. As an officer in the First Order, Rivas possessed the skill to fly a TIE/fo fighter. Rivas viewed the R'ora of Luprora as uncivilized due to their mistreatment of him during his captivity. As a consequence of his imprisonment, Rivas sustained a bruised right eye and various facial scratches. When Captain Phasma attempted to force him into falsely admitting his involvement in Starkiller Base's destruction, Rivas remained resistant and attempted to negotiate for his life by offering to remain silent. Initially believing he'll be spared, he then realized that Phasma meant business, Rivas' defiance gave way to fear and desperation. To cover up her role in Starkiller Base's destruction, Phasma executed Rivas.
The character of Lieutenant Sol Rivas made his debut appearance in Star Wars: Captain Phasma, a four-issue comic book series published by Marvel Comics in 2017 as part of the Journey to Star Wars: The Last Jedi promotional campaign. He was brought to life by the creative team of Kelly Thompson (writer), Marco Checchetto (illustrator), and Andres Mossa (colorist).