Brex Eilentes is the older brother of Euryce, and his twin sister is Lasan. He is the only son of Maishan and Westry Eilentes.
As a child, Brex would tease and torment Euryce. It was their sister Lasan who softened the effects of this, and she prevented Euryce from outright despising Brex. His teasing included making unkind comments on Eury's childish naïveté and excluding her from games. On a far more egregious occasion, he delivered news of her hero Roima Gotharom's untimely death in a blunt and insensitive fashion (→TRD).
Brex joined CAGA after completing his mandatory education. His current whereabouts are unknown. He is presumably embroiled in the war against Voice and his allies, and could potentially have been one of the soldiers deployed to the restless worlds. If this is the case, he could now be under the control of Voice. Euryce Eilentes has been unable to contact him for some time (→FSS).