AN: I do not own Harry Potter.
Also, I warn about death, mild gore, and anything else you might find disturbing. THERE IS DEATH MENTIONED MULTIPLE TIMES AND MULTIPLE WAYS.
Alternate Endings For The Potter-Slytherin Curse
1. My Original Ending I Didn't Use Because I Thought It Was Too Similar To A Father's Letters
Harry and company find out about the curse and decide that they should try to end the war by having peace through the factions. The curse is starting to affect sooner as well. Because of this, the Order is more desperate to find a cure, but Harry just wants the war to end. He goes to Slytherin and makes peace with Draco, finding that book earlier as well. The Weasleys go along with it, and Snape, who would rather his sworn loyalties not fighting each other. There is The Christmas Gathering, in which the Weasley family as a whole swear loyalties to Harry. Harry reaches out to the Dark Lord through letters being passed on through Draco. They make a truce. The war stops between the Order and Voldemort. Harry and Voldemort find a ritual that will allow them to protect those in their families or those loyal to them, and turn to stone snakes outside their respective homes.
2. Alternate Ending To My Original One
The family curse draws the two struggling partially stone snakes to an ancient temple, where the magicians there keep an eye on the struggling duo. They could both turn to stone before the fight ends. Harry could lose, because he's the one without multiple Horcruxes, and Voldemort becomes human again (full soul and body and mind). Voldemort could win temporarily, and only kill the horcrux like in canon, and then have another four years before this happens again; in this case either of them dying right away is probably guaranteed.
3. The Obscurus Is Real (With One Or Both)
In one of the fights, because they become worse once they get to school, Harry or Dudley or both loose his/their obscurus (es), resulting in the death of the majority of the population within the surrounding area. Somehow having Dumbledore connected to the wards means that those inside most of the building are safe, but it doesn't save everyone. Either one or both of the boys die, (the horcrux in Harry's scar may or may not hold him together, you decide) as well. The Dark and Light sides urge their leaders for peace, which happens as they clean up the aftermath of losing one quarter of the wizarding world's future because "they aren't that bad".
4. The Ending Ritual For Voldemort and Horcruxes Kills Harry Too
Harry screams as the magic of the ritual pulls him in to the middle too, a black glowing miasma around his head. One of the other teens fills Harry's spot in the chanting. They can't stop if this is going to end well now. Voldemort zooms in, pulled by the magic, and Harry clings to him. If he's dying, his fated enemy will die too. The green fire comes up and burns them to ashes in seconds, as well as the black smokes that are pulled into the circle. The world mourns both of them.
4b. They try to stop the ritual, but the magic gathered kills everyone gathered. Draco wasn't part of this, as his parents insisted as an only child. Harry and friends insisted so that there would be somebody who could carry on if it didn't work. When he and his mother come in, everyone is obviously dead, with blood scattered throughout the room. The war starts up again without any of it's mitigating factors, and both sides viewing their fallen leaders as martyrs.