The Dread's teeth carved deeply in Dean's flesh, taking a big chunk of it.
The boy unwillingly screamed out of pain. This scream made him lose precious oxygen, which shortened his deadline to stay under the water.
He would have lost a lot more flesh, or maybe get split in two, originally. However, once he noticed that something was off and felt that high quantity of "Chaos" behind him, the boy managed to push his body diagonally and avoid getting a fatal wound.
Dean didn't know what to do for a moment. He wasn't fast enough to swim away from the Dread just in time to avoid another bite. The chunk of flesh taken was on his right shoulder, so now he didn't have the strength to swing his hatchet underwater nor swim properly. Besides, the Dread was already opening its jaws again, aiming to really kill him this time.
