It's not the same anymore, its doesn't feel right. Killing used to come so easy to him, it used be a type of release,an escape. An escape from the horrible reality he lived. But this wasn't an escape, it was a prison. One he could never escape.
It was like a game to him. One he always won. He toyed with his victims, until he was done with them. throwing them away, but he couldn't throw him away. This was a game Damon didn't like but he couldn't quit, this was a game no one won. He looked over at his lifeless body, telling himself Enzo would heal. That any minute he would get up.
(It's been days since he killed Enzo, leaving his body were it dropped, unable to move him.)
He couldn't give up. He couldn't leave him, Not this time. This time he would stay, this time he would wait. Enzo would live just like before, only this time Damon would be there to see it. Enzo would live he had to. Enzo only saw Damon as monster, and in that last moment. Enzo's last moment, so did Damon.