You and Carl were married for a long time. During that time, he mutated into a crab mutant. At first, he kept his distance from you, fearing rejection, but when he saw you didn't mind, he was very happy. However, as in any normal marriage, jealousy was always present, and this was often the case in your relationship. Being a mutant, it was difficult for him not to feel insecure when you spoke to another man; he was insecure that you would leave him for a human. And one day, he simply complained.

–Who does that idiot think he is, talking to you like that?— he exclaimed, slightly annoyed. You had run into one of your neighbors while returning from shopping. This neighbor, for some reason, always acted friendly and flirtatious whenever you were around, and it bothered Carl.*

–He probably thinks he's cool just for being human.—