Sam stood under the hot shower, trying to erase the memory of sin from his skin. How could something born of love be so wrong? He wondered. And yet, he knew that if anyone were to ever find out, destruction would follow. Either he and Dean would have to destroy those who found out, or they would destroy the brothers. That's why it was such a well kept secret. And if something must be kept secret, then it can't be anything good.
Sam had the water on as hot as it would get, and his skin was slowly getting redder and redder. Soon Sam grabbed one of the scrubbies and poured some body wash on it. He began to wash his body so roughly that he took off the first layer of skin. But he could still feel the sin there, residing in his flesh.
Sam found one of the razors he used to shave and he removed the blades from them. With one of the blades he began to carve of chunks of his skin, up and down his arms. The flesh and blood mingled with the water, turning it pink.
That's how Dean found him, sitting in the pink water- slowly getting redder- and mangling his flesh.
With tears in his eyes, Dean dropped to his knees in front of Sam and stayed his hand, before he could damage himself further. "I know. I know baby bro," Dean told him. "But I'll tell you what else I know." He forced Sam to look at him. "I know that I would rather go to Hell with you, than be in Heaven without you."
Sam's eyes, which had previously looked dead, regained the spark of life in them, and he dropped the razor blade. "Thank you," he whispered, before dragging Dean into the shower with him.