Sans

History
Despite his seeming lack of effort, ever since landing in the Pit, Sans has been hard at work. However he ended up here, there had to be a way to reverse it. He was not the first, nor the last to arrive here from another universe entirely. In fact, it seemed the numbers continued to climb. Void was the main culprit, but was hardly the only possibility. He probably got dumped here through some multiversal shenanigans. Normally, jumping through the void wouldn't pose an issue- but it actually bothers the hell out of him. He doesn't dare go far from this place, despite the awful circumstances. Something brought him here, so sticking around might be the only way to get back to his brother, Papyrus.

It took a bit of effort on his part, but conversing with some of the others who had come here from other universes unveiled a lot. For instance- he could always tell who had been human or humanoid based on the amount of digits on their forelimbs. Previous humans always had five, as did his alternate versions. But just because they had five fingers, didn't always mean they were exclusively human in their world. The mute Executioner had five digits on each paw, but that thing was far from any human Sans had ever met.