Sam had never been the same after Jess's death.
Dean kept pestering him, trying to get him to lighten up, but Dean didn't know about Sam's inner guilt.
Ever since that fateful night, Sam had been spiralling downward on his own personal guilt-trip, stuck in an endless loop, never being able to stop. The nightmares alone haunted him, never leaving him alone, making him bury himself even deeper in the pit of despair that threatened to drag him under.
Every time he was reminded of Jess, the darkness threatened to engulf him again. It took all of Sam's willpower to not give in, and it was starting to show. Dark shadows were under Sam's eyes, and Dean was getting concerned.
"You should seriously get some sleep." Dean had said to Sam, getting a grumble in reply.
What Dean didn't know what that it ran deeper than just sleep deprivation. When Sam did sleep, he was subject to the nightmares, making him wake and not sleep for the rest of the night. It made Sam feel so guilty about what had happened and the despair gripped him so tightly he turned to the only thing he knew.
Sam was glad of the cold weather, as he could wear his hoodie and the sleeves covered the bandages of his wrists. He was ashamed of his habit, but he found it helped him cope. Every time he felt he couldn't bear it, he would go into the bathroom and add a few more cuts to his wrists, silently sobbing as he did so.
It was at times like these that he was partially glad for the lifestyle he lived. Bandages, antiseptics, and anything else that may be needed were in abundance, and Sam was no stranger to taking care of wounds.
Eventually, Sam knew that Dean would find out, and when that happened, Sam knew that Dean would be upset and scared, but Sam knew that Dean would probably cover it up with anger.
Sam didn't want to put Dean through that emotional turmoil; the guilt of not being there for his baby brother when quite obviously that was what he needed. Of course, Sam knew that there was no way Dean could know, but Dean, upon finding out, would undertake his own personal guilt-trip.
Sam decided one night that he was going to stop it. Stop the hurt, the guilt, the torment, the despair. Sam was strong willed, and he managed to last through that night. That night was the longest night ever. The next day, he was in a decidedly happier mood, pleased at his achievement, although he was extremely tired.
A few months later, Sam was happier and hadn't had a fresh wound for weeks. He knew it would still take work, but he knew that he would get through.
His new-found determination had been spurred on by the recent development of his feelings for Dean. He had cared for him, but now he found he was in love with him. This made him even more determined that Dean would never find out, as he couldn't bear hurting Dean yet again. He knew he'd never forgive himself if he did so.
Dean never found out. Never found out about Sam's habit, Sam's feelings for him, Sam's emotional turmoil.
Although, Sam knew that someday, someday he would let Dean know.
But not just yet.
