Thon and his brother Reff were both born on Sanghelios in the city-state of Thasanee. The latter was considered to be weaker than most Sangheili males, but Thon saw something special in him and watched out for him his entire life.
Line Installation 1-4Edit
- Main article: Battle of Line Installation 1-4
When the two brothers joined the Covenant, Thon rose through the ranks to becoming Shipmaster of the Covenant CAS-class Assault Carrier Clarity of Faith, with Reff by his side. While attempting to rendezvous with a supply convoy in Sub-Sector 35, the ship picked up a transmission that displayed a Pi-constant, not used by the Covenant or the humans. In a fit of religious fervor, Reff took this to be a sign from the Forerunners and a signal that the Great Journey was imminent, and insisted that they must investigate. However, Thon ignored his brother and ordered Clarity to make a Slipspace jump. When they jumped, a sudden burst of energy sent the Clarity crashing down onto an unidentified moon. Once again, Reff started preaching about the Great Journey. Thon slammed his brother against a bulkhead and scolded him for speaking heresy. He further warned that if Reff ever interfered with his command, he would personally gut his carcass.
The two brothers donned Ranger armor in order to survey the airless moon. Scouting the landscape in a Wraith, they encountered a team of Spartans and engaged them. The fight was interrupted by Gatherers, which captured Reff, an Unggoy, a Mgalekgolo, and Black-One. After reaching Line Installation 1-4, Thon and the rest of his men allied with Black-Three and Four in order to rescue their comrades, held prisoner by the installation's Monitor, 686 Ebullient Prism. While still on their way to rescue their compatriots, the truce between the Covenant and the Spartans was tested as the Monitor tried to turn them against each other.
Meanwhile, Black-One and Reff managed to escape captivity and evade the Monitor, eventually making their way to the facility's control room, where Reff contacted Thon. Upon reaching the control center, Thon had a Mgalekgolo slam Black-One into a console, stating that the truce with the humans was over now that he had retrieved his brother. Thon then noticed the supply convoy they were originally supposed to escort approaching their position in Slipspace, and inquired if they could use the installation's machinery to contact High Charity to send teams to claim the artifact.
However, Reff proclaimed that they must instead use the installation's main weapon to shoot the convoy down, claiming that it was destiny that brought him here to build a "new Covenant." Thon rebuked him, reminding him that Reff had only survived because of him. Refusing to tolerate his heresy or let him stain their family name, Thon proceeded to kill his brother. However, Reff stole Thon's energy sword and impaled his brother with it. Reff was vaporized by the Monitor soon after.
While Reff was shown to be fanatically religious and driven by emotion, Thon was more clear-minded and practical, often ignoring events his brother took as holy signs. Despite their differences, Thon cared for his brother deeply and did not want any harm to come to him. However, Thon was still unquestioningly loyal to the Covenant and their religion even more so than to his brother, as demonstrated by him not hesitating to kill him for speaking heresy.
- Halo: Blood Line (First appearance)