I have made this account for, precisely, this moment ( hi by the way, binged this fanficiton some days ago ), to share this idea.
PS: I numerated all points so it's easier to talk about them.
PS: english is not my first language
I was trying to guess how this will end as we don't know how many years it will take ( the waiting sucks ) but for how things are proggressing, year four will be when EVERYTHING goes wrong. It's when death eaters come back, people start dying and voldmort is resurrected. I also think viridian might be lying about somethings ( JKRowling did too after all ) when he talked about harry not being a horcrux anymore. Doesn't make much sense on how can Tom's soul have been "squeezed" by the time travel. Two things could have happened:
1-Voldmort's soul came back to voldmort. This would be a great plot twist, as both Harry and Voldie would be time travellers, both with increased magic cores (although Harry would hold advantage bacause Voldie would only gain a eight of his soul back) and both with fore knowledge.PS: Harry would still be an horcrux, it wont affect the one already implanted.
2-The piece of Vold's soul just stacks on the already present in Harry's body. This could have many consequences: the connection between the Chosen One and the Dark Lord would be a lot stronger and/or Tom would be slowly receiving his future's memories.
This, however raises a problem. Wasn't it established that future Harry won? Yes it was........ or Harry though it was! You see, after destroying every single horcrux and Voldmort himself, Tom Riddle, realizing that all his defences and secrets were broken, rested inside Harry, never revealing his presence. But how could the arrogant son a of bitch, mass murder, hide himself like a coward inside his greatest enemy? Two things come at play here:
3-Riddle respects Harry. Yup, that's right, Harry Potter, after more of a decade of fighting, become a ruthless and powerfull killer. Tom thought of him as a kid, but as time went on, harry grew up. When he killed Voldie, it was The-Boy-Who-Lived, it was The-Man-Who-Survived-Fucking-13-Years-,-Killing-Half-My-Army-As-Well-As-Defying-Me-Successfully-More-Times-Than-I-Can-Count-And-Killed-Me. By the end of Harry's life he was feared by all, he would pile up Death Eaters every time given chance without the slightest hesitation: he became Voldmort's image on the side of "light" ( cause that shit ain't light )
4-Because of this development in the way, I'm not sure if actually feared Harry, but he certainly wasn't going to challenge him for his body...not while he was strong. When Harry got in the depression, Riddle started planning for the perfect moment to take over his body, until, of course, Harry had the brightest idea of the world: let's travel back in time! It was perfect for Riddle as Harry would never suspect that he was a horcrux after "seeing" voldmort die without the need to kill himself and he would also keep his memories, guaranteeing revenge.
However, if Point 2 would be the correct one, how would he "leave" Harry's body? When Harry goes after Quirrel, Voldmort tries to use leggimency on Harry during the conflict. Although Harry successfully protects himself, he doesn't protect Voldmort's soul ( heck, that might not even be possible ), taking us to Point 5:
5-This would actually be against cannon, as surely, Voldmort also tried then the same leggimency but because his souls wasn't from the future, he never received different memories. Therefore, he never felt....different. But now, after doing on Harry, things changed as he received a very different feedback, consequently, became aware of the future.
Now, with that covered, how can Harry react? Well, my guess is that he will either discover it at the end of book 4 ( the climax of things going down the hole ) or during book 5. Both of them will happen with a lot of emotional stress as he will realize that he never defeated Voldmort: the prophecy might not be real. This will such panic on Harry as well as self-guilt ( everyone died for him because he was the chosen one, and in th end, he failed to do the very least they all expected ) that SUICIDE starts to feel reasonable. All his foreshadowing suddenly became useless as whatever he does, it might not matter at all! EVERYONE IS GOING TO DIE AND HE CAN'T DO SHIT ABOUT IT ( YUP, FATE IS LAUGHING, IT PERFECTLY FITS THE IRONY OF THIS FANFICITON ).This takes us to Point 6:
6-If the Deathly Hallows are not to be part of this story, this means Harry Potter will die. Furthermore, Harry will realize that they were wrong. He is not the Chosen One, Neville is.He won't share this secret with many people, maybe Hermione, Ron and Sirius but Neville for sure ( maybe Dumbledore too, but I have no idea how thing will be for this old man), He will feel so much guilt that he won't be able to tell Ginny ( yeah, its selfish, but then again... people are not perfect, and Harry with all his PTSD is far from it, which will only worsen). Harry and Ginny will have some bumps in their relationship ( PEOPLE WILL DIE ), but it will only cause it to become stronger. Harry will eventually see her as "his" Ginny, causing again a massive breakdown of guilty when he discovers he might not be capable of killing Voldie, thus can't, in any way, guarantee her safety.
7-Harry will use the Sword of Godric to create a weapon capable of annihilating horcruxes, infecting it with poison still usable on the Chamber ( in cannon, Ron and Hermone, after all, on year 7 they used the basilisk teeth to destroy one, so the poison still works ), making sure to leave something to take care of possible future problems. His paranoia will start imagening that Tom has even more Horcruxes.
In the final battle ( could happen at the Ministry, end of book 5....or not, doesn't matter ) harry will kill himself ( not the first time ) with Godrics Sword during the fight against Voldemort, with Neville taking the final shot. I think at this point they will need to be on good terms with Dumbledore, he could help them a lot at this point. After DD learns the true nature of the prophecy he won't be able to obliviate Harry, it's just too risky.
8-Harry dies for the greater good ( ultimate irony with Dumbledore ), leaving Ginny sad and heartbroken................................yeah, ladies and gentleman, we've got a sequel: Ginny goes back in time to save her loved one, thus guaranteeing a continuation to this amazing story.
Well, find my plot holes and discuss ( the bigger the theory, easier it falls)
Cheers!
Desert Fox