Regalia

The "tattoos" on his body, and the dye in his tail and hair are actually three ink demons who serve him. If you look long enough, The tattoo will shift and move slightly, and the eyes will blink. The ink demons accompany him and uses their power on his command. The ink demons can temporarily take over bodies by covering the body in it's tattoos (wherever the tattoo touches becomes under their control) even together they are not strong enough (or brave enough) to overcome Regalia, and would not be able to control his body unless he were completely unconscious. 

 You can tell the ink demons apart by the color of their dye, and the color of their eyes.

When the ink demons leave his body, Regalia is entirely black/grey except for his skin color and eyes.