Thexan and his twin brother Arcann were born as princes to Valkorion, and trained from a very early age in combat. With his younger twin brother, Arcann, he joined the Zakuul Knights at a young age. Both of them were sensitive to the Force, and were able to use it very effectively in combat. As they grew, both built and used lightsabers as their primary weapons. Upon reaching adulthood, the brothers proposed a plan to test the strength of the border worlds between Zakuul and the holdings of the Republic and Sith Empire. Valkorion sanctioned the assault, but allowed only Thexan to lead the Eternal Fleet. Defying his father's orders to remain on Zakuul, Arcann joined his brother at the front.
The two led the Eternal Empire's armed forces to war against the Galactic Republic and Sith Empire, driving them back almost to the brink of extinction. Arcann was wounded severely in the face and lost his left arm while waging a battle on a Sith planet, and Thexan stood by his brother and held him as a medical team worked to stabilize the injuries.

Arcann and Thexan eventually returned to Valkorion, presenting lightsabers of both Jedi and Sith as trophies of their successes in battle. When Valkorion turned away without so much as a glance at the weapons, the light of the dark side ignited in Arcann's eyes as he became furious at his father's lack of caring. Irate, he ignited his lightsaber and leaped at his father, intending to cut him down. Thexan, using the Force, pulled Arcann back in an attempt to prevent his father's death. Arcann, furious, turned his fury on his brother and dueled with him briefly. Arcane lashed out and struck his brother across the torso. Thexan glanced at his brother with a look of resignation, and the light of the dark side faded from Arcann's eyes as he realized what he had done. Thexan fell, but was caught by Arcann at the last second and cradled as he died.