Born in Byroden, she and her older twin brother Vax'ildan, were raised there by their mother Elaina until they were taken to live in the elven city of Syngorn at the direction of their father, Syldor Vessar. She and Vax'ildan were unhappy, and left in their early adulthood to be on their own. In their travels, Vex'ahlia rescued a bear cub, Trinket, gaining a loyal animal companion.

Vex is the more pragmatic of the twins. She is very deceptive and can usually bluff her way through various social encounters. Her charisma has also made her good at haggling. Her tendency to haggle stems from her frugality. Her frugal nature is the result of Vax and herself having to fend for themselves during their teenage years. Unofficially, she is the treasurer for Vox Machina, and often only gives cryptic answers when questioned by the group about how much gold they have. But beneath her flirtatious attitude, self-confidence, and outgoing exterior lay a girl who feels broken and unwanted.

Voice example: https://youtu.be/_b1oZmPrpDg?t=717