Peto Kelsan, a Human officer serving in the Imperial Navy, swore allegiance to Darth Krayt following the deposition of Emperor Roan Fel by the Sith Lord in the year of 130 ABY. Elevated to the rank of admiral, Kelsan assumed command of the Coruscant Third Fleet. By 137 ABY, Kelsan's fleet was stationed at Ralltiir, a Core World of considerable importance as a major financial hub within the galaxy. In that year, Ralltiir was attacked; forces from the Galactic Alliance Remnant—the former galactic government, overthrown by the Sith and Roan Fel during their alliance—confronted Kelsan's forces. Admiral Gar Stazi led the Galactic Alliance forces, who were soon reinforced by the Bastion Second Fleet, under the command of Edouard Fenel of Fel's Empire.
Faced with the overwhelming numerical advantage of his adversaries, Kelsan reluctantly yielded the Coruscant Third Fleet to Fenel. A moral dilemma arose when Captain Vaclen Tor of the frigate Steadfast defied the surrender, reminding Kelsan of their obligation to prevent the fleet from falling into enemy hands. Kelsan ultimately disregarded Fenel's subsequent command to target the Steadfast, instead ordering the Third Fleet to initiate self-destruct protocols and evacuate to Ralltiir via escape pods. Unexpectedly, Gar Stazi then directed his forces to shield the Third Fleet during its evacuation, preventing Fenel from firing on the vulnerable escape pods. After the crews had safely evacuated, Kelsan expressed his gratitude to Stazi before activating the self-destruct mechanisms on the warships. The Admiral remained aboard the Avenger and perished as the warship detonated above Ralltiir.

Peto Kelsan was a member of Emperor Roan Fel's Empire, holding a position within the Imperial Navy. This Human was acquainted with Admiral Edouard Fenel. In 127 ABY, Roan Fel, alongside his Sith allies led by Darth Krayt, launched a war against the ruling Galactic Federation of Free Alliances. Following the war's conclusion in 130 ABY, Darth Krayt and his Sith Order overthrew the Galactic Alliance, betrayed Emperor Fel, and attacked him. Fel fled Coruscant, the galactic capital, allowing Darth Krayt to seize control of the planet. In the aftermath, the Imperial Navy fractured, with Peto Kelsan among those who pledged their allegiance to Darth Krayt, who then placed him in command of the Coruscant Third Fleet with the rank of admiral.
Kelsan directed the fleet from the bridge of the Avenger, a Pellaeon-class Star Destroyer captained by the Nikto named Furske. By 137 ABY, Kelsan's forces were assigned to defend Ralltiir, a strategically vital Core World and a major financial center in the galaxy. The Imperials believed the planet was unlikely to be targeted, as neither Roan Fel nor the Galactic Alliance Remnant seemed to possess sufficient warships.
However, during that same year, the fleet commanded by Chief of State Gar Stazi of the Galactic Alliance Remnant emerged from hyperspace directly in front of Kelsan's fleet, engaging it at close range. Stazi's forces overwhelmed the Coruscant Third Fleet, targeting the engines and defensive systems of Kelsan's ships to disable and capture them. As Kelsan's fleet activated their shields and returned fire, the Admiral requested a report from Captain Furske, who stated that the Avenger's engines had been damaged before the shields were raised. Despite knowing Krayt's forces had superior firepower, Kelsan was puzzled by Stazi's sudden assault. The two fleets continued exchanging fire until the reason for Stazi's daring attack became evident: an Imperial fleet aligned with Emperor Roan Fel emerged from hyperspace and joined the attack alongside Stazi's forces.
The combined enemy fleets outnumbered Kelsan's forces, and the Avenger's shields sustained damage under the renewed assault. Admiral Edouard Fenel soon contacted Kelsan directly. Fenel acknowledged Kelsan's promotion to admiral before requesting a ceasefire to address the Coruscant Third Fleet. Defeated, Kelsan agreed and allowed Fenel to communicate with his command. Fenel issued an ultimatum, demanding Kelsan's forces surrender within ten minutes or face complete destruction, and invoked Fel's authority to order Kelsan's crews to eliminate their commanding officers if they refused to surrender.
Kelsan reluctantly announced that the fleet would comply with Fenel's demands. However, to the surprise of both Kelsan and Fenel, one officer of the Coruscant Third Fleet—Captain Vaclen Tor of the Ardent-class fast frigate Steadfast—disagreed. Tor announced over a general frequency that Kelsan's orders were unacceptable, declaring that the Coruscant Third Fleet owed its loyalty to Emperor Krayt. The Captain directly addressed Kelsan, reminding him that it was their duty and a matter of honor to prevent the Third Fleet's warships from falling into enemy hands.

Enraged, Fenel initially ordered Tor's crew to kill him, and when that failed, he ordered his entire fleet to open fire on the Steadfast. Already conflicted, Kelsan refused to fire upon the vessel despite Fenel's repeated orders. Instead, Kelsan chose to order the crews of the Third Fleet to ignore his previous surrender order and initiate the self-destruct mechanisms on their warships, before evacuating in escape pods and fleeing to Ralltiir. The Admiral decided to remain on Avenger to cover the evacuation and go down with the ship, but Fenel then broadcast an order to fire on the Third Fleet's escape pods. To Kelsan's astonishment, Gar Stazi defied Fenel, positioning his warships to protect the Third Fleet and refusing to fire on the defenseless crews.
Once Stazi's forces were in position and prevented Fenel's fleet from attacking, Stazi contacted Kelsan personally to inform him that it was safe to begin the evacuation. The crews of the Third Fleet abandoned their vessels en masse; once everyone was clear, Kelsan initiated the fleet's self-destruct and informed the Duros admiral. When Stazi inquired why Kelsan had not boarded an escape pod, Kelsan replied that his place was aboard Avenger. The Admiral thanked Stazi as the Third Fleet warships began to explode, ultimately perishing as Avenger was destroyed.
Peto Kelsan possessed a pragmatic nature. During the Battle of Ralltiir, the Admiral recognized that Stazi's bold attack had underlying motives. When facing superior enemy numbers and firepower, Kelsan opted to surrender rather than engage in a futile battle. Kelsan could not fathom making the same decision as Stazi to defend an enemy as they fled a battle. However, when his values were challenged, the Admiral abandoned pragmatism and chose to uphold his sense of honor and duty. Refusing to fire upon a warship under his command, Kelsan placed the Avenger in harm's way to protect the evacuating crews. Rather than join in the retreat,
Admiral Peto Kelsan made his debut in the thirty-sixth issue of Star Wars: Legacy, titled Renegade, published by Dark Horse Comics. The issue was authored by John Ostrander and illustrated by Omar Francia.