A Happy End-I

Esther and Beelzebub shared glances, an unspoken conversation was exchanged by them with their eyes. Beelzebub raised his hand and caught the demon by his neck, pulling him which would be better described as dragging him across the floor. 

"Now show us the way, will you?" Beelzebub's words sounded like a request but to other's ears and after the bloody mess he caused, it was a pure threats.

Esther made one last eye contact with Beelzebub and followed him. 

Who is it? This person Reviys is someone they don't know but it doesn't seem the same to him. Based on how he had laid a trap to rouse Beelzebub's interest means he knows Beel deeply enough to know his deepest nemesis.