Nightmare Sans

He is often deceitful, erratic, unpredictable, and vicious. Nightmare once told Cross and Dream that many villains were brought to their knees, including Horror, Dust, and Killer. Dream has noted that when Nightmare was younger, he was very smug, which Nightmare himself vehemently denies. Nightmare! Sans is, in general- sadistic. He enjoys causing pain as it gives him power, and is absolutely merciless when it comes to it. Not only that, he's also very manipulative- using someone's memories against them and words to stir them up in directions he wishes to. He's disgusted by positive emotions. If he can't make them negative, he'll just leave, since it weakens him. Because he only has one eye to see, he has a blind spot.