Today is Nathan's birthday, so here's some info about him...Nathan's hand tattoo of owlfeathers is actually a sign of his being marked by Athene, a voluntary commitment he made to her when he was just starting out in his realmwalking.  He found several details of her and her practices appealing, and he wanted to avoid a far less desireable Forcemark, so he got this instead!

This, I imagine, is him examining his new 'tattoo' just moments after receiving it from the priestess who gave it to him.