OKay, so I went through my FF.net favs and this is all the dark fics that I found that have them still in Hogwarts. Some I haven't read in awhile so sorry if their not exactly what you are looking for. All are bottom draco and dark harry though... I think...
https://www.fanfiction.net/s/1944410/1/Change Dark!Harry. He is also angry at the light side. Draco kinda ends up helping him I think.
https://www.fanfiction.net/s/2043742/1/From-Green-to-Black Harry runs into Draco after killing his uncle (Or everyone) and they become friends and later they get together. Harry gets really protective of Draco
https://www.fanfiction.net/s/3067213/1/Harry-Potter-and-the-Twist-of-Life Dark harry. son of Severus. Draco doesn't like his father. creature fic
https://www.fanfiction.net/s/2678088/1/Stigmata Harry becomes a dark lord so that he can be together with Draco
https://www.fanfiction.net/s/9283538/1/The-Black-Star Harry is sick of the light side after Sirius was killed.
https://www.fanfiction.net/s/6606862/1/The-Son-of-a-Dark-Lord AU. Harry is raised by Lilly and James, but they are not his parents. they have a son so Harry has a sibling kind of, but Harry doesn't really like any go them. He is the son of Voldemort and gets really dark and Draco is Harry's everything.
https://www.fanfiction.net/s/3380186/1/Wolf Harry is raised by someone else after Lilly and James where killed. he kind grows up with draco and they are mates. there is kinda a lot more blame shutting onto Draco every time they fight, so if you are like me you can find one or two of the chapters a bit frustrating.
no subject
https://www.fanfiction.net/s/1944410/1/Change
Dark!Harry. He is also angry at the light side. Draco kinda ends up helping him I think.
https://www.fanfiction.net/s/2043742/1/From-Green-to-Black
Harry runs into Draco after killing his uncle (Or everyone) and they become friends and later they get together. Harry gets really protective of Draco
https://www.fanfiction.net/s/3067213/1/Harry-Potter-and-the-Twist-of-Life
Dark harry. son of Severus. Draco doesn't like his father. creature fic
https://www.fanfiction.net/s/2678088/1/Stigmata
Harry becomes a dark lord so that he can be together with Draco
https://www.fanfiction.net/s/9283538/1/The-Black-Star
Harry is sick of the light side after Sirius was killed.
https://www.fanfiction.net/s/6606862/1/The-Son-of-a-Dark-Lord
AU. Harry is raised by Lilly and James, but they are not his parents. they have a son so Harry has a sibling kind of, but Harry doesn't really like any go them. He is the son of Voldemort and gets really dark and Draco is Harry's everything.
https://www.fanfiction.net/s/3380186/1/Wolf
Harry is raised by someone else after Lilly and James where killed. he kind grows up with draco and they are mates. there is kinda a lot more blame shutting onto Draco every time they fight, so if you are like me you can find one or two of the chapters a bit frustrating.
Hope some of them are to your liking :)
-Cat