His mind burns with rage, and he grits his teeth together, balling his hands into tight fists with claws that rip through his own skin. It's all he can do to keep from full out attacking everyone within reach, and ruining his cover. He manages to keep himself hidden in the background, though.

It subsides, eventually; and the slight sting in his hands makes him glance down with surprise -- and he sees indigo staining them. The anger in his head wavers.