Board Thread:Fun and Games/@comment-27524978-20160317154321/@comment-31204808-20160426004244

Fanon Sans: A depressed skeleton who is bad at hiding his emotions and has some kind of ectoplasmic flesh. Has a blue flaming eye that glows in combat. Probably used to be a human.

Canon Sans: A nihilistic (but far from depressed) skeleton who, even when Papyrus is killed, doesn't show much emotion, as he expects you to reset. Confident that you will give up during his battle. His eye flashes teal and yellow when using telekinesis. Only implication that he was ever a human is the fact that he is a skeleton, though everything points to him and Papyrus just being (insectoid?) monsters that resemble human skeletons.