Sans can be harsh and rude. He is not really into puns, but likes knock-knock jokes. He is under constant stress, hence his red eye highlights. He strives to keep calm. He is shown to have a temper at times, hinting at a strict upbringing from his father, WingDing Gaster. He is allergic to cats. He is very rude, blunt, and sometimes comes across as a jerk, but is a big softie underneath it all. He secretly likes cherry-flavored things. He sells hamburgers, fries, and chimichangas.