Geno is very manipulative and will continue to manipulate Sans to gain his trust after erasing his mind over and over until he finally gets his way.He is also very sensitive about Papyrus and will not let anyone touch his scarf. When Sans brings Papyrus with him on his visit to the Save screen, Geno becomes furious.While he can be quite violent, he still has a sense of humour, and his first reaction to seeing Sans is to make puns.The right half of His skull is melting.