She grew up on Betazed under her tyrannical mother's care and while still fairly young, forced to marry Anton Mil, a Terran, and live with him on Earth. She took this chance as an opportunity to escape despite the husband chosen. In this time she raised Cara Maria and bore the majority of Anton's abuse in silence.
Anton's father refused to let Cara have a Betazoid surname, hence why the first was used, making her Maria-Mil. She works as a linguist, specialising in translating legal documents and closing the loopholes that can form in translation. She is also a strong telepath, but rarely needs to use it.
Like all Betazoids she has black hair and eyes, and looks similar to her daughter, but taller and more graceful, despite the fact she's only two inches taller and the shortest of her sisters, so more than a touch spanish. She tends to move with a contained confidence, with the knowledge that she can manage to live her own way despite everything thrown at her. However she is kind, and years of practice enable her to act submissive when needed.
She is often described by the other two sisters as having a 'flame', in other words determined and strong-willed. This is probably the reason Josephine decided to send her away with an abusive husband to try and teach her manners, however she has now become somewhat of a liability if she finds out Josephine is trying to manipulate Cara. When she is particularly annoyed she gives a glare and lets that irrepressible personality show through, though normally she holds it in or hides it entirely.
As an escaped free spirit herself she stands by the motto "live and let live", unless of course it means letting a bully go. She will do anything in her power to help a victim, though prefers to do it quietly and subversively, as she is good at that.