Renau, as I understand it, Caerwyn is Talashia's big brother. During their childhood he tended to look out for her, since she attracted negative attention due to her oddity and how strange events followed her. Once she left the village to go train her magic (this happened while she was still fairly young), Caerwyn took his ideals of individual liberties on the road, becoming a thorn in the side of more than one self-important local lord.
He and Talashia reunited by seeming coincidence during this game, when she left mage school to hunt down what she needed to begin her 'transcendence.' I forget what Caerwyn was in town for...
But yeah, feel free to tweak things as needed for your own unique take on the character. I'll change Talashia's background description to suit it.