I think this was more of a fantasy series, though it was more subtle than The Lord of the Rings IIRC. Set in modern times - though there was some alternate realm thing that was less modern I think.
I read it about ten years ago, I think, and there were a number of books at that time. My brother and I stopped reading it shortly after the main character summoned a small demon somehow who was a bad influence... I think.
It involved a boy who somehow was at some kind of training school/academy. Unsure where it was located, but it needed a classic portal to get to it I think. I clearly remember some scene involving a car driving at specific speeds to get past some barriers. There may have been something about how the school was (slowly) moving or the wards were shrinking... unsure. I don't think it was only magic based, but that was some element of it. The boy had some kind of strange power that made him an incredible fighter, but he wasn't sure how (at least from what I remember). The recordings of him training just showed a white flash I think. I remember some scene in an elevator going down to the training floor where he went to a level below some adult with him.
There was something else about him joining a group that had twelve members, one for each month, whose powers grew and lessened based on how close the date was to "their" month.
Oh, and there was something about him looking for his mother I think? Perhaps in another "realm"?
Any help is appreciated!