Im imagining this would span an entire 5 year period at hogwarts (18 university) but would be interesting to see it somehow squeezed into less time, say 1-3 years

Harry is still the boy who lived however he never learns that slytherin is “evil” therefore he never asks the sorting hat to place him “anywhere but slytherin” , the sorting hat then places him in slytherin knowing he could be great.

Hermione, with this deep rooted hatred caused by bullying because she’s a mudblood, has this desire to prove herself and be great , using anything and anyone to achieve power including her intellect. I imagine she has this bad girl vibe.

Draco, terrified of becoming like his cruel parents, begs the sorting hat to place him anywhere but slytherin, so he gets placed in gryffindor.

Ron stays basically the same , gryffindor, and he eventually befriends Draco as Draco is kind of an outcast , no one particularly likes him because he’s a Malfoy in gryffindor, except Ron befriends him and eventually sneaks Draco out in the magic car every summer , Ron’s parents, hesitant to accept Draco at first, eventually end up treating Draco as family ( instead of harry in original) together they both feel a kind of hate for harry because he’s thus living legend in slytherin, even though Draco more or less feels jealous because of Harry’s relationship with Hermione.

Ginny placed in slytherin , is the outcast of the Weasleys and makes more sense when she’s writing stuff on walls in blood and is Tom riddles puppet (she still develops feelings for harry as they are both in slytherin but it doesn’t work out because Hermione is in the way.

So all of that aside the main plot is Hermione becoming obsessed with power and trying to follow in voldemorts footsteps, using and manipulating harry to help her achieve that goal and having a secret affair with Draco all while being with harry. Draco wants nothing more than to snap hermione out of her craze for power and show her she can be loved for who she is, but harry is in the way because Hermione refuses to let him go because of his soul tie to Tom Riddle and his ability to talk to snakes etc

Hermione at some point manipulates harry to ask slugworth about horcruxes (making him relive his memory of Tom riddle [ another slytherin] asking about them) except harry is not asking for his own sake but rather for his “love” Hermione.

Eventually after secretly sneaking around with Draco and falling for him, she starts to feel like he’s a distraction to her true purpose - power. Therefore she starts spending time with death eaters ( a lot happens in between all this ) and learning more about Voldemort, she tries to forget about Draco and focus on harry and in her final pursuit for power, she tries to force / convince harry to get her pregnant so she can bear his seed ( the tie to Voldemort ).

Hermione has become too troublesome and powerful so somebody has to stop her. After not seeing her for months Draco unites with harry in hopes of finding her and “saving” her. When they realize she’s too deep into her dark powers they realize they must kill her before she causes harm to anyone else. Harry uses the kill curse (learned it since he’s in slytherin) to kill Hermione after he realizes he has been manipulated all along , he’s angry and feels vengeful , Draco tries stopping him convinced there’s another way around this but Harry doesn’t listen. Hermione dies, but in those last moments Hermione has flashbacks of her life realizing power wasn’t worth it and that Draco was the most important to her , but now it’s too late. She lay there dead, however they realize she’s pregnant (Harry didn’t know she was because she disappeared for many months) they rush her to the hospital wing and the baby magically survives (the girl who lives). Harry and Draco both are puzzled by the whole scenario but decide to both equally take responsibility for the child and raise her together.