Harry discovers new abilities on his fifteenth birthday, and so accidentally ends up going to the only people who can help him train this new gift.
Harry is jealous that Tommy gets such a cool name. This is the result of a sugar high... so it's really, really random.
What if Harry had turned out more like Tom Riddle after being left with the Dursleys? A bitter child genius, with a wish for revenge... It's no wonder he turned to the dark.