Well, I'm not a guy so I don't understand the intricacies of the male physique. However, I have met guys who seem to just have abs. Sometimes really skinny guys have the visible abs just because there's no damn fat on them. I could see that being the case with Vaan. Or maybe he just has good genes. ^^

On a side note, the hottness that is Basch looks awfully scrawny when you first get him from the prison. Does he bulk up when he switches into his main outfit, or is his body type the same throughout and maybe the beard through me off?