In my stories, the Dark One used the Force Dyad of Rey and Kylo to spread his Darkness before he can conquer the Galaxy. He made a plan that would expose Palpatine, his rival, and give him the advantage in any result of the battle. But some things went wrong for him...
1. Kylo Ren died
For an imprint to stay alive, both members must be alive. Then Palpatine killed Rey and put a wrench on that. And then, Ben showed compassion for a human being that wasn't himself and gave his life to Rey. This didn't just destroy the imprint, it also made Kylo suffer some punishment, as him having a happy ending would make people look up to him, and made Rey free in her own mind and able to become her own Jedi.
2. Rey found a life beyond her abuser
The Dark One might have handed Rey power, but really didn't care about her. He planned to make her a weak willed pawn that submitted to Kylo and pushed away from her anyone but the grandson of Vader and the demon king, but physically strong enough to do such mistakes with no consequences. Then he wanted her to create a delusional Jedi Order that followed his Dark values in the name of the Light. (Sith? Who trusts the Sith to serve him?) However, he didn't expect the Dyad to break with Kylo's death, or fade away slowly. So, his final attempt to get Rey to isolate herself in the desert to mourn or kill herself failed.
3. Finn just kept undermining him
While Rey was weeping that nobody knew her, Finn kept proving her wrong again and again and again. When she started pushing him away with increasingly violent means, both Finn and Poe realized something was wrong. At a few points, Rey even trusted her friends, especially Finn, over Kylo, something that was not the Dark One's preferred outcome. And then Finn inspired Jannah and other Stormtroopers, and their revolution stopped the Sith Fleet as much as the Dyad did, doing so much history couldn't erase it. That way, the slaves that stood up for themselves found a voice. And above all else, Finn got the Force, thus the potential to become a Jedi, and contributed enough in Exegol to be able to gain confidence and carve his own path.
1. Kylo Ren died
For an imprint to stay alive, both members must be alive. Then Palpatine killed Rey and put a wrench on that. And then, Ben showed compassion for a human being that wasn't himself and gave his life to Rey. This didn't just destroy the imprint, it also made Kylo suffer some punishment, as him having a happy ending would make people look up to him, and made Rey free in her own mind and able to become her own Jedi.
2. Rey found a life beyond her abuser
The Dark One might have handed Rey power, but really didn't care about her. He planned to make her a weak willed pawn that submitted to Kylo and pushed away from her anyone but the grandson of Vader and the demon king, but physically strong enough to do such mistakes with no consequences. Then he wanted her to create a delusional Jedi Order that followed his Dark values in the name of the Light. (Sith? Who trusts the Sith to serve him?) However, he didn't expect the Dyad to break with Kylo's death, or fade away slowly. So, his final attempt to get Rey to isolate herself in the desert to mourn or kill herself failed.
3. Finn just kept undermining him
While Rey was weeping that nobody knew her, Finn kept proving her wrong again and again and again. When she started pushing him away with increasingly violent means, both Finn and Poe realized something was wrong. At a few points, Rey even trusted her friends, especially Finn, over Kylo, something that was not the Dark One's preferred outcome. And then Finn inspired Jannah and other Stormtroopers, and their revolution stopped the Sith Fleet as much as the Dyad did, doing so much history couldn't erase it. That way, the slaves that stood up for themselves found a voice. And above all else, Finn got the Force, thus the potential to become a Jedi, and contributed enough in Exegol to be able to gain confidence and carve his own path.