Harry Aizen: A Soul Reaper in Hogwarts.
It was the end of July, Harry Potter's birthday. However, People only cared about his twin brother, Leon Potter, the "Boy-Who-Lived". During the Halloween when they were one year old, their parents left for a meeting in the ministry; their father's friend, Peter Pettigrew, acting as babysitter. But Peter was a traitor; he sold the refuge to the Dark Lord, Voldemort.
-The babies are here, master. – Said the fake babysitter as he guided his lord to the twins.
When they reached the room, the dark wizard attempted to use the killing curse on Harry first, but the spell backfired and destroyed Voldemort's body. There was a huge explosion and pieces of the house were falling everywhere, Peter ran away in a hurry. Their parents, James and Lily Potter, as well as Albus Dumbledore arrived and ran to check up on the children. When they entered the room, Albus noticed that Leon was closer to the Dark Lord's cloak and came to the conclusion that Leon was the one who defeated Voldemort. Since then, nobody but the house elves paid attention to Harry.
End of the flashback.
Harry was five years old and he was much smarter and mature than anyone his age. He knew why his parents, as well as Sirius Black and Remus Lupin, who were Leon and Harry's godfathers respectively, ignored him and he hated it, his brother rubbing it in his face didn't help things along.
That night, he went to get a snack, when he overheard a conversation between his parents and the man who dubbed his brother the "Boy-Who-Lived", Albus Dumbledore.
-Are you sure it's a good idea, Albus? – Asked Lily.
-Of course, Harry has not shown any sign of accidental magic, so it is better to transfer his magic to Leon to give him a boost to help him when Voldemort will come back. – Answered the leader of the light.
-He's right Lily. Don't worry, I made Leon the family heir and you know doing that means disowning Harry from the family, permanently. – Reasoned James.
Harry was angry. If they actually paid attention to him, they would have known that the reason he didn't show sign of accidental magic was because he already controlled it. It was all he could do to pass the time. But whenever he did magic, his parents thought it was Leon's doing and praised him instead.
There was only one thing he could do now: run away. He gathered everything in his room and left through the window.
He eventually ran into an old man who gave of a feeling of trust.
-And what is a little child doing out here in the middle of the night? – He asked.
For some reason, Harry was unable to lie and told him his life with his "family". The man was furious and took him in. He wouldn't be seen until he became eleven, old enough to go to Hogwarts.