Derek wades out into the water and feels the chill overtake him, and then turns around to watch Thomas approach. He tries very hard not to look at him too closely, but he can't help it. He looks even less like Stiles like this. He's tanner and leaner, muscles a little more defined.

He swallows hard and looks away for a moment, the tips of his ears pink, and then looks over again when Thomas speaks to him. "Dunk your head under. It'll help with the cold."

Derek sinks under the water and at first the cold shocks him, but then it evens out and he resurfaces with a smile, lifting his arms to push his hair back away from his face.