A monster? A king? What is he?

"Now, why don't I go and get Serena out of here?" John asked as he looked at the room they had just had their fight inside. 

His eyes slowly lost their bright yellow glow before going back to being simply clouded in darkness. 

As this happened, John shadow stepped the front of the room which had been broken before looking over at his arms. 

They were shaking, not due to fear but because of what he had done. 

It was different from the feeling of killing someone, John naturally became able to kill people as he knew that the concept of souls and reincarnation existed. They would either go to a better place in heaven, or suffer in hell. 

On top of that, Possession clouded his emotions making him more numb to events whenever he was in it. Which is why he would always use it when he steeled himself to commit the act of killing someone.