<Snipped quote by harinezumikouken>
Actually I've been meaning to ask, why is that? Don't get me wrong it's badass and everything but is it like a genetic trait, part of his semblance, a manifestation of his aura?
Genetic trait. It's purely aesthetic and serves no purpose other than "Uh-oh, Shiro is feeling some kind of way/in 'combat mode'".
Before, in the old HoB RP. It used to be tied to his Semblance, where when his Semblance is active the 'stripes' appeared. And if you laid eyes on them, you were trapped in his debuff/illusions. But for logical reasons and for balancing reason, I changed that up.
Now, it just looks cool.