Light returned to his black eye sockets and Sans stared at the ceiling of his old room. Blue tears were slowly forming in the corner of his eye-sockets. His memories were intact not a piece missing and he knew why. This would be true fully their very last run and he had to make it count. He would keep that damned Flower away from his Frisk even if it was Asriel to some point...

An alternate ending to Undertale. To get this ending one would need to complete one Genocide run and a few pacifist runs before getting this phone call from Sans. Going as far back as the 1st human's descent into the underground, this story is very spoiler heavy and contains themes of suicide and some swearing and ideally, would be the way to save a timeline from a genocide run.

This shouldn't have happened, it was just a hiccup in the timelines. Then again, Frisk should have known things weren't going to so be perfect for such a while. Underfell AU. Obvious spoilers and older fem!Frisk

Sans always watched the timelines reset. Because of a freak incident, the timeline was contaminated. A mysterious figure told him he had to go in and destroy the hate, but this timeline was more than contaminated. Everyone was dark, twisted. One by one, Sans must save the Underground, before the Underlord destroys him...but who is the Underlord? UnderFell AU

Things had been well in the underground. Frisk had broken the barrier, made the monsters friends, family. There was finally, at long last, peace. That was until they reset. Again, and again, and again. Sans is now determined to put a stop to it, once and for all.