Skull's Forgotten Memories

Skull was made an Arcobaleno, but why? He's weak and childish. But what happened to bring him into the circle of people who are the world's most lethal and powerful babies? But the better question is why doesn't he remember what happened before that, why do none of them? Reborn knows, and he has answers that even concern Aria's father. Will the two sky Arcobaleno's can weather this