I want to see a story where the villainess wakes up, gets out of bed, walks down to the basement where she whips up a bomb, arranges to have a tea party where everyone who betrayed her in the previous life, and straight up fuckin' murders them. Using the chaos of the massive death toll, the villainess proceeds to use the deaths as a sacrifice to rip open a hole to another universe allowing countless demons to rampage and murder with glee.
You know... a happy ending.
The problem with most time regression stories is because evil people are still evil. I have helped people who fucked up their entire lives, got them back to square one, only to watch them immediately make the exact same mistakes assuming that THIS TIME IT WILL WORK. I actually like villainess stories, but I don't believe the assumption that they will actually change. Because they won't.
Now if they lived their life, had regrets then were the ones to roll back the clock, then yes, they MIGHT change, but a villainess sent back in time because "reasons"? No. You can't help someone who doesn't want to be helped. If the will isn't there to change to begin with and they had to work and sacrifice for that change, it won't work. A gift that is earned with no effort or sacrifice is not valued. Most villainesses would just flush the new chance right now the drain.
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What I want to see is a version where the time regression from the beheading of the villainess takes place, except everyone in the immediate area regresses as well. The King and queen, the prince, the villainess, the saintess, the reverse harem for the saintess, and the villainess' entire family who were beheaded with her at the time.
But nobody else.
So the king might wish to immediately kill the villainess' family, but in the past the Duke and his family was MUCH more powerful, so these two groups have to face off. The prince and the villainess are still engaged. The saintess is in some orphanage. The King and Queen realize the solid position they were in doesn't exist. The mine of gemstones hasn't been discovered.
But then there are many forces that are acting on both parties that were pushing both to fight so they could weaken the country for take over.
So when the duke basically prepares to start a civil war, the outside party who didn't regress immediately step up to help them, which seems rather sus to the duke, who puts it together that the two were manipulated against each other and so they have to reunite to defend the country.
The problem is, even if they had Iago whispering in their ears, the still were assholes to each other. The duke still abused his daughter ruining her personality. The Prince still cheated on the villainess with the saintess. The saintess suddenly realizes that becoming the saintess completely torpedos any hope of having a normal life. The reverse haram realize this is their chance to steal the saintess from the prince.
Oh... that would be grand.