Hiei prefers to keep his distance from others, so he often comes across as aloof and elusive. He has a rather cynical and even misanthropic view of the world around him, often belittling and mocking humans and their emotions and the significance they place on friendship and life.

Cold and calculating, with logic as his fundamental basis. It is very difficult to gauge his emotions from looking into his single cold red eye, which comprises his face and head.

Sans Undertale

portrayed as an eccentric individual. His dialogue is rife with maniacal laughter, repeated words, rambling puns, and strange sentences, and he has a sadistic sense of entertainment, considering battle with the party to be a "GAME." He has a very cynical view of the world around him and considers everyone around him to be trapped while he is the only one truly free, despite ironically being jailed from the world.