One of the reasons Caius has for being so quiet and calm all the time is an ability he isn't even aware of. During the time of the month when the Full Moon is around, he tends to have "blackouts", as he calls them. When his passion is overflowing in some way during this time, he tends to get big and beastly. He usually prefers being left alone for a few days, as the strength he has in this form is monstrous. It's rare he that he's seen by others like this however.