Here is my concept for the apprentice I'm thinking of. I might make some mistakes here. I'm giving adult stats and Virtues and Flaws, but I'll indicate the starting ones when she comes to notHogwarts.
She is a young girl from France, in a farming villa near the mountains. She was loved by her family despite the Gift, but others were not so fond of her, and many believed it was she that set the fire which burned down the stable and killed several horses. If she had not been found by Hermetic recruiters she might have been killed.
Mythic Blood: Phoenix
-Minor Focus: Aging
-Coat of Flame (Touch)
Greater Immunity: Fire
Unbound Tongue (HoH: MC pg 38)
*Higher Purpose Rebirth of the Order
Deficient Technique: Perdo
Low Self Esteem
Susceptibility to Divine Power
*From Mythic Blood
**I can see this as being a consequence of the School atmosphere. One of the unintended consequences of group learning. Perhaps this flaw starts popping up among other students and the curricula needs to be adjusted. The ones underlined are Virtues and Flaws I see her starting with.
As a result of her Visions and her perceived destiny she often feels pulled by forces outside of her control. Her own choices have less consequence because she often worries that she is not even making a choice; her path is before her. She is very pious and fearful of her power and offending the Lord, but at the same time she feels she has a great and perhaps terrible purpose for the Order. A weakness that influential magi might be able to use is that she is more of a follower, a charismatic magus could easily get her under his sway.