Book series about a girl with magic ability; her brother is revealed to have magic ability towards the end

Question

In 2009, our teacher used to regularly read us this book series about a girl with some sort of magic powers and her brother, who has none. I remember very little other than a few fragments.

At one point, it seems like her and her brother are on the run from something but I don't remember what, I think they had to drive a van to get away?

Towards the end, the girl has to use her powers to defeat the enemy who had been hunting her and her brother. I think the enemy was some kind of witch who was intimidated by the girl's powers growing? Anyways, during this fight, it's revealed that the brother actually does have some kind of minor power and I believe he uses it to help his sister in this fight.

I know there were at least two or three books in this series. Unfortunately that's all I remember, I don't remember how the books looked at all, since I wasn't the one reading it, but I'd love to know if any of those fragments resonate with anyone as I remember really enjoying the story when I was younger!

Answer 1

You may be somewhat misremembering the Chrestomanci books by Dianna Wynne Jones. In one of the books ("Charmed Life") the boy, named Cat, and his sister, Gwendolen, are orphans who go to live with the great sorcerer Chrestomanci because the sister wishes to train her magic.

Per the question, it does turn out that Cat has magic in the end. Unlike the question,

his sister is not at all magic and has been stealing Cat's magic the whole time. His sister is very much the villain of the story and is involved with a plan to sacrifice both Cat and Chrestomanci in a ritual to open doors to other worlds, a ritual complicated by the fact that Chrestomanci and Cat (as his name has been hinting) have multiple lives. By realizing his own magic, Cat manages to free Chrestomanci and stop his sister's plot.

There are six books in this series, revolving loosely around the life and actions of Chrestomanci. One, "Magicians of Caprona", has him as a secondary character in a variant of Romeo and Juliet.