Delli was the fetus of a nun, Sister MacGuines, who was aborted in Salem Hospital when their abortion wing was new... but after his untimely demise, God grew angered with Sister MacGuines and told the devil he may have free reign over the dead child's soul to exact justified punishment to any mother who would have their child killed inside the womb. Delli was brought back to life, twisted and angered, he dragged doctors and nurses into Hell through gateways made of blood, but he gave his mother a second chance without realizing that it would create a weakness. 

Delli is very vengeful but will not take children. The only thing that can calm him down is his mother's lullaby, but it only works for a short moment of time. He has the ability to bring other aborted infant souls to aid him in dragging his victims to Hell, giving them bodies made of blood.

If you ever find yourself running from Delli, sing that lullaby and leave anybody you are there with behind, they are most likely gone already...