Solution!Tale is an AU which takes place at the end of a genocide run right before Chara appears and the human resets. But right after the protagonist kills Flowey, Alphys appears and says the following:
H-H-Hu-Hum-Human? AGHHH! PLEASE DON'T H-HUH-HUH-HURT ME! Oh yes you must be very confused. Well I don't know how to describe this, but before you awoke from your fall I saw your genocidal grin. And just in case you did go all out, I kept experimenting. And finally I made it.... SOLUTION!!!!! Solution is this robot that goes around and collects souls right before they fade away and makes them new and improved bodies. And it collected all the souls of the souls of the monsters you killed. But, there is a problem, stupidly I gave it a mind of its own and it found the human souls. And like it was supposed to, it gave them robot bodies too. And they did something they regret.... THEY AWOKE CHARA! And they fought her and won. Of course solution had to, "Solve". And then Chara in her robot form gave the souls less power and the robots more. So every time they see a human or a monster (A soul in control) it will well you know, "Solve" or should I say, make you a evil robot body. So for your genocidal actions I will send you back and your journey will be WAY harder with the "Solved Monsters".
So basically it is like all the souls are evil and have robot bodies and instead of killing you they "Solve" you, and give you a robot body too.
This AU Is Currently Incomplete