Sans is a huge alcoholic who makes very disturbing and rash decisions. He enjoys making jokes, even if they don't make sense or if they are incredibly offensive. At times he will be upset if no one laughs, but most of the time he does not care. Sans can be smart in some instances as well as being eerily serious, mostly because of his weapons garage and alcoholism respectively. He can also be hypocritical, as he continuously threatens Frisk not to harm anyone, even though he killed a jelly thing.