- "Appealing to Def's vanity was a surefire way to make him agree to almost anything. It was something of a fatal flaw in his character, but at least his loyalty overrode that sort of thing in dire situations - so far."
- — Thoughts regarding Tieradeff "Def" Jaggeron, by Jex Sirri
Tieradeff "Def" Jaggeron was born and raised on Ailon, among his own people. He was raised to praise military training and skill in combat above all else. He pursued membership in the Ailon Nova Guard, but was denied admission. He departed his homeworld in an emotional state, vowing not to return until he had proved his strength. Eventually, he joined the crew of Ragnar Starflight and the Purgatory's Escape as a security officer, which provided him with the rank of Lieutenant. While there, he became close friends with Omwati officer Jex Sirri.
Because of a shortage of crew, Def was one of the officers assigned to a gunnery station during a battle with Mashaka Vargo and his Liberators. In an attempt to escape Vargo's forces, the Purgatory's Escape encountered Solace Station. The colonists there allowed them access, and Def was one of the first officers to board.
When Sirri was one of the soldiers headed down to the depths of the station, Def was frustrated that he was not allowed to accompany him. Instead, Def remained on the upper levels of the station, where he became the de facto head of security for the smuggler crew. He found himself playing politics more than anything else, at first, and he wished Sirri were present instead.
As the situation degraded on the colony, Def found himself making executive decisions against violent colonists, notably Jakob Marle. He began to wish fervently that he were a mercenary or bounty hunter, instead of a security officer. By the time Marle committed suicide under the influence of Rakatan spirits, Def had taken to calling the station "Hell Station."
When Werro Prell began an open insurrection against the smugglers, Def was in charge of keeping the peace. He chose to stun and capture the violent colonists wherever possible, but his natural instincts were to kill at the risk of being killed. Fortunately, Gideon Corey and his crew completed their mission and disabled the station, freeing the minds of the colonists.
Afterward, Def was made the official chief of security for the Purgatory's Escape, and promoted to the rank of Sergeant.
The First Kurasian Rebellion
When the Ryn Freyel requested Corey's assistance in liberating the planet Kuras IV from the clutches of crime lord Breggar Lark, Def jumped at the chance to see some real action. During the First Battle of Kuras IV, Def led a strike team of twenty soldiers to kill Lark and rescue undercover operatives Arelim Seron and Jag'Tai Vroenik.
When the battle was over, Def was one of the commanding officers present for the founding of the Kuras Tetrarchy; however, he volunteered to join Eric Noble and the mercenary Yerrix in leaving the world on the Wayfarer, instead of returning to security duty.
Shortly after leaving Kuras IV, Def and his companions met former Stormtrooper Arlan Hale on Svivren. Hale joined the mercenary crew, and in the time that followed, the Wayfarer traveled across the Galaxy, smuggling and engaging in mercenary work wherever they found it.
One of their smuggling missions led them to Dysag'aven, a Lethan Twi'lek who believed he recognized Hale, but called him Losian. After learning more, the crew went to meet Losian's wife, to whom Hale swore to return. Def questioned him on this, suggesting that he would never be back, but Hale was firm in his vow.
Shortly after the Battle of Coruscant in 16 ABY, the Wayfarer made it was way there in pursuit of information on a planet called Baehorde, apparently the treasure world of long-dead pirate Whit Solomon. There was not enough information to go on, however, so Def and the crew continued searching for nearly a year. During that time, Def improved his Basic enunciation, weakening his formerly severe Ailon accent.
Eventually, they found the planet and set a course. When they arrived, they discovered an entry chamber with a large amount of treasure stockpiled therein. They also discovered a servant droid, once belonging to Solomon himself.
Meanwhile, Rethe Frettan in the Blade of Fate, accompanied by Xen'Chi warrior Sar'Preyvor and Chosen Shan Tslav, pursued them, looking for Hale. The Augur, belonging to the Scautus Order, was also enroute to the planet. When they all arrived, a battle ensued between the agents of the Scautus Order and the friends of Arlan Hale. The crew of the Wayfarer escaped the battle with the help of the droid they found.
The droid led them to the personal chambers of Whit Solomon, where the pirate was being kept alive with a number of medical machines. When the droid realized that neither Hale nor any of his companions understood Hale's purpose in seeking out the planet, he imprisoned Def, Noble, and Yerrix. Briefly, Def suggested that Hale had been lying to them about his identity and reasons, but the others quickly convinced him otherwise.
A short while later, the three mercenaries escaped from their cell and ran Frettan, Preyvor, and Tslav, who accompanied them to the main chamber of the base. There, they were confronted by a small army of droids designed to protect the base from intruders. When Frettan suggested that those present were his companions, the droids determined that all were impostors and intruders and deserved to die. When he thought his life was about to end, all Def could think about were his lost opportunities.
But Hale awoke before the droids attacked and he commanded them to stop. After introducing himself as Solomon, he ordered Def to accompany him on the Freeborn Knave while they escaped the planet. Once again, Def lamented not being able to participate in the more dangerous mission.
The Second Kurasian Rebellion
After escaping Baehorde, Def returned to the Wayfarer with Noble and Yerrix. They worked with Solomon on the Freeborn Knave to capture Scautus prison ships enroute to the Drift. One such ship housed Emma Zacharias as a prisoner, and Order agents Scur and Rakka, who had been present at Baehorde. Def was trapped, along with Noble and Yerrix, in the engine room.
Eventually, they escaped, but only after Scur and Rakka stole the Wayfarer and fled. Def joined the others on the Freeborn Knave.
During the Third Battle of Kuras IV, Def was one of the soldiers who joined the attack on the Nomad. When Solomon was confronted with the mercenaries under Mortrassa's employ, Def moved with Noble, Yerrix, and Zacharias toward the bridge. They blasted their way into the bridge and took control of the situation. He was therefore present for the death of General Enscu, and for the duel between Kiuwo and Kratyn vuv Enerkerraz.