Indeed, Kenneth wanted to kill Charlie right there and then.
However, he realized that it was not wise to act impulsively—the mighty dragon was no match for the native serpent.
He knew clearly that he was no match to Charlie right now.
It seemed that Charlie was quite powerful and strong, meaning that he had to be skilled in martial arts and self-defense.
It was very hard to go after a man who was knowledgeable and tenacious. He had to get someone who was on par or more powerful than Charli