Dom, Nic. Or maybe “Demonic” if he’s being naughty.
Famous people named Dominic:
Actors Dom Sherwood, Dominic Purcell, Dominic West, Dominic Cooper, and Dominic Kay; football player Dominic Raiola; director Dominic Sena.
Because of its meaning, the name Dominic was traditionally given to little boys born on Sunday.