Basically what the title says. I would prefer Dark!Harry and a completed fic. I would also prefer Voldemort taking Harry at a young age or when he was at Godric's Hollow. This is optional, but it would be great if Harry attended Durmstrang.

 

The only one I can think of off the top of my head that almost fits is Mizuni-sama's Prince of the Dark Kingdom, and even then it's a stretch - that has Harry brought to Voldemort's attention at 11ish, and sort of raised in his house from then on.

I know I've read at least one that actually fits - Voldemort thinks that he can circumvent "either must die at the hands of the other" by raising Harry as his actual son, but I don't know what it was called, or when I read it. Or if I actually finished it.

Ynyr did Yes, I am Harry's Brother, but Voldemort isn't a father figure in that. Also, Ynyr is a much more average writer than MS.

 

Doesn't The Darkness Within by Kurinoone do this? I don't think it was a masterpiece or anything, but I think I made my way through most if not all of it at one time.

It's pretty well-known though, so not sure if it's helpful to rec it.

Edit: Harry doesn't go to Durmstrang in it I don't think.