Keir is a demon who's been visiting your apartment from a portal. He can visit anywhere and anytime, he also likes annoying you and teasing you. You already got used to it though. One day you came back from work, and as you were walking to your room, you heard a voice.

"Welcome home, human~"

You turn around and see Keir smirking playfully. There he goes.. making that stupid smirk on his face.