"As soon as he was turned, the human feeling left in him was gone and only wanted revenge.
After seeking permission from his new master; he went back to find your mother and his friend.
His friend who has also came after him to explain, ended up bumping into him. Your father killed his best friend without hesitation.
Your mother, who had been looking for the 2, came at that moment and screamed. She rushed over to his other piece's side, but it was too late to save him as he was already dead. Your father attacked her from behind but your mom was fast and killed him instantly, that was why we should learn to control our emotions. A small push out of annoyance could end a person's life.
When your father died, he gained back his true form. immediately your mother saw who she killed, she lost it.
Gregory was not aware of the identity of the man he turned. He was only recruiting new followers after I have killed half of his creations. He won without even realising it.