Killer!Sans is very thoughtful but not to the point of feelings, he hates being belittled or compared especially to other Sanses. Generally a negative to neutral character, although Killer loves cats and had two before Nightmare killed/attacked one for making Killer positive. Killer also seems to suffer from some type of personality/identity disorder similar to DID. He'll have little breakdowns and freak outs when he's beginning to feel again and is reminded of the pain he's caused.