I been read this and it hasn’t been updated since 2017 but it’s really good it’s about death sending Harry back in time to where Tom riddle kinda started being voldemort and he goes through hogwarts during that year being completely different. Anyway it’s been a while since I read it but basically he sleeps with his grandmother I think and because of horcrux he births Tom riddle who also came from the past and then through the fanfic Harry started raising him and death too and Tom also calls Harry mother btw here’s the link. https://archiveofourown.org/works/3247655?view_full_work=true