I didn't find anything that fit perfectly your prompt, and I don't have the time now to write some :/
But, here:
https://www.fanfiction.net/s/9591343/1/Some-Other-Beginning-s-End
I think this is great, only a one-shot though. Harry reveals to Voldemort that he's a Horcrux during the final battle and they go on to live immortally ever after.
https://www.fanfiction.net/s/6163339/1/Harry-Potter-and-the-Descent-into-Darkness
This starts early, and is a melting pot of wrong and hot. And it has a sequel - plus Athey is a goddess so check her stories if you don't know her.
https://www.fanfiction.net/s/11261111/1/Pieces-of-my-Soul
Just one chapter for now, but beautiful. A piece of Voldy's soul gets a body and finds Harry, then it's all kinds of cute, possessive pre-slash. Before Voldemort enters the mix.
https://www.fanfiction.net/s/9290286/1/Death-s-Son
Another from Little Miss Xanda (check her out too), if you like do-over fics, this is it. Harry loves being a Horcrux. Plus - Barty.
https://www.fanfiction.net/s/5563431/1/Dabbling-With-The-Dark
This isn't exactly what you asked for, but 112,461 words and complete, so...
Hope this helped feed the craving
Lady's Daughter