Rowan is a predator, he was so young, yet his ledger was already dripping red with the blood of countless billions.
After becoming an Ouroboros Serpent his nature had turned cold, and he did not turn bloodthirsty, only apathetic. He had fought a hundred battles and won every single one, he was sure of his strength and he feared nothing. This was not pride, this was simply confidence.
Every action he took was carefully planned, because he knew he was very powerful and to kill him would be extremely difficult but he still understood that his downfall would only come if he was careless.
He was powerful but he was not invincible. He just needed time to become one. No one else could make a claim like this except Rowan.