Her origins were unknown and as a child she was adopted by two attorneys Gene and Karen York. From early on her nanny noticed that she was very strange and when a photo was taken of her there was strange colors around her. Delia was known to be very negative and at times even violent. When Karen tried to find out who Delia's real parents were strange events occur and Karen gets injured.
Shortly after Karen's baby Alex is born she learns of Delia's true parents and believes she will become the antichrist, but she later finds out the Delia is just a protector, she finds out that when Delia was born she had a twin brother whose DNA was implanted into Karen so Karen gave birth to Alex who was really Damien Thorn the Antichrist now reborn again as an infant.
Karen then tries to kill Delia and the reborn Damien Thorn infant who has 666 on his hand. A gunshot is then heard and the next scene is at Karen's funeral. Delia stands holding her baby brother who is Damien the now reborn antichrist.