A piece of Voldemort's soul attached to baby Harry Potter that fateful Halloween night. Over the years, the soul piece witnessed how much danger and pain his host was in. How far would the soul go to protect the child he began to care for, especially when the boy started to care for him in return? Oh, just a little over-protective care, some magic training, maybe some necromancy...
This is a quite good story with a few downsides. The author is so visibly american by their misspelling (and variant spelling) alone, but also by some concepts… but the plot progresses well enough and is rather very interesting. It takes quite some time initially for there to be visible changes from canon (but the author probably was too lazy to bat a butterfly’s wings), but then, with the change, Harry is all that more Gryffindor than he was in canon, most of what Snape always accused him to be, more daredevil, fuck the consequences, like… despite him also being a model Slytherin.