Xaoc

A demon from another plane, bonded to Ylldove Cartrana and manipulating her to assist in his plans to enter the Material Plane. He has pledged friendship to Ylldove, and given her loneliness, that has been enough to earn her loyalty.

Ylldove is not his first warlock, having previously had a similar relationship with the being now known as Cackling Agatha.

Looks a little bit like Jake Gyllenhaal, just with yellow eyes, vertical pupils, and a jagged smile.