Geno

CQ's first son but he's still the shortest. He suffers from a magic deficiency.

Apparently, he has more than 2/3 of his soul missing. That is causing breathing problems, pain, weak body, etc.

He doesn't like seeing his brothers unhappy, hurt, or both. In a flashback, after "Pepper" Bullied Error, he beat Pepper and broke their leg. He also tries to hide his pain from Error a lot, but since he is a kid, after all, he can't hide it very well.