The water did not wash away the smell of his fear, it only gave it another dimension and soon Derek was crashing through the water. His own lust had taken over. Stiles would probably be pissed at him after he found out that he set this up, if he ever told the boy.
He saw the boy up ahead and growled low in his throat. Yes, he would tackle the boy and rid him of them clothes. He did wish that Stiles had come to him. Then he could mount the boy and fully own him. He could still have some fun with the boy.