Seraphine Ziemniak

Seraphine Ziemniak is a brat. And also a Centurion and a natural magician with an innate power quite beyond her own understanding or control.

While Madam Czarna may be the last patrilineal member of the ancient Twardowski aristocratic family-and-magical lineage, the matrilineal lie was of course broader and somewhat less doomed. Of course, in most of them the magical power did not manifest to any extent, or merely flickered and died before long. But one day, a devout Polish-French family living in rural, God-fearing Picardy was cursed with the horrible affliction that is Seraphine Ziemniak. Fortunately for them, the early manifestations of her power were yet mostly survivable, and before things could get worse a kindly man named Albrecht Falkenrath came by to take this wretched monster off their hands (and presumably drown it in a lake).

Unbeknownst to them (not really, considering the beard, and the clothes), Albrecht was himself a powerful magician, if of a rather different sort, his abilities acquired through study, hard work and a fair amount of blind luck. He took Seraphine to be raised in an even more remote and parochial place than Picardy, training and watching her to make sure that she would develop a way of controlling her powers. And making her run various minor errands and do chores for him.

That didn't quite happen though she did get somewhat better at it with time. On the other hand, she also got stronger, so the slip-ups in her control were all the worse. Perhaps this was the true reason Albrecht sighed and rejoined human society, dragging Seraphine with him to Stockholm to the Conference of Magicians. There she met a spooky Chinaman named Lin Tsao, set some things on fire, met more wizards than she ever wanted to, helped Lin fight monsters, and then got thrown in a magic fridge for her own good.