Help me find this story PLEASE!

It is about an AU where Neville is the bwl and Harry is a daywalker. Harry ran away from the dursleys when he was 9 and was bitten by a vampire, but didn't become one. He is a loner and doesn't have any friends at Hogwarts, though he has a friend who is a slayer.

I think it is set in Harry's fifth or sixth year, Sirius is free and is teaching defence at Hogwarts. Ron and Hermione are friends with Neville, there is a scene on the train where they are trying to remember what Harry's name is.

If you know the story please tell me!

Thanks

LotusFlower17