Sans X reader OneShot
You're both tired, both at the end of your strength. But after years of being held captive by Chara, you use your final moments to take control and save the underground.
When Frisk follows a genocide route, Sans does everything he can to bring her down. But with a power like "reset", even he eventually falls to her mercy. However, instead of killing him, she offers him a chilling deal that will change his life forever.