A/N: Title comes from the song "What You Don't Know" by the band Monrose.

Disclaimer: All character do not belong to me. I do not make profit from this story.

Sam slowly sank down on the edge of the stained bathtub. He carefully took the blade to his left arm, making sure to stay well away from his wrists. Hesitating when the knife didn't seem to stop moving, he looked up to calm himself. The haunted eyes of his reflection from the bathroom mirror seemed to mock him and stare him down. Worthless.

Choking down a sob, Sam looked down at his arm again and applied pressure on the blade resting there. Shame trickled down his spine. Up until a week ago, he hadn't done this since he was seventeen and the pressure of hunting just became too much. Apparently, now a grown man, he still hasn't learnt to deal.

The blood finally welled up from the shallow cut he'd made. Fascinated, Sam stared at the small rivulets of pure red flowing down to his fingertips. "That's the only thing that's at all pure about you", his brain supplied.

Now with tears adding to the sting of the cut, Sam moved the knife higher up and put more pressure behind the next cut.

The edges of the wound burned as if held over fire. More blood dripped onto the greyish floor tiles. Everything that was wrong with him, that was tainted, finally left his veins.

When the pain registered in his spinning brain at last, Sam moved and leaned against the door to the other room. And, thank God, all the thoughts just seemed to disappear from his mind.

Sam closed his eyes and reveled in the complete silence. He felt boneless and hazy and tired. Tired of hunting, of moving and, most of all tired of the guilt he carried for letting Dean down all the time.

A jolt of shock made Sam flinch when he heard rustling from the other side of the door. Afraid Dean would wake up soon and start looking for him, Sam moved to stand up. His knees were still wobbly, though, and he had to steady himself on the sink.

He glanced up at the mirror. Worthless. Impure. Jerking his head down, he quickly cleaned the wounds, relaxing at the lasting throb from the water. Wrapping them with some gauze from the special first aid kit he still had for this from his teenage years, Sam made sure to get all the blood off the demon knife.

He'd discovered that little detail the last time. The demon knife from Ruby interacted with the demon blood in him and added to the pain. Really, he should've seen that one coming. He was tainted, after all.

A slow cold ache spread though him, this time only emotional pain. Pain he couldn't control, just the kind of pain he wanted to cut out of him…

Calming himself a little to keep from openly sobbing or crying hysterically, despite feeling substantially better after… well... Sam quietly got out of the bathroom and after tucking everything back to its rightful place he got into his own motel bed facing away from his brother.

Another thing he clearly should have anticipated. Still, his heart clenched and he felt like he couldn't breathe. Dean had reverted to booking motel rooms with separate beds ever since he got out of Purgatory. At first, Sam thought it was just to avoid awkward questions out of tiredness.

But then Dean really slept in his own bed and didn't crawl into Sam's as he used to. Dean didn't kiss Sam, Dean didn't touch Sam if it wasn't totally necessary. His brother never even really looked at him anymore.

The coldness and distance grated on Sam's nerves. Determined to shut out all the painful thoughts and ignore the guilt in his heart, Sam closed his eyes.

WYDK

"Sam? Wake up."

The noise was hazy and Sam didn't want to listen, didn't want to give his sleep-induced peace up.

"Sam! You with me?"

Acknowledging that it was Dean trying to get him awake, Sam slowly let consciousness pass over him. Moving to sit up, he groaned at the harsh light and rubbed his slightly swollen eyes.

"Yeah, I'm awake. What is it?" Sam saw his brother standing beside the small table, packing bags. Packing usually meant moving, which usually meant a hunt. But Sam couldn't be sure, Dean never liked staying in one place for long.

"Where's the knife, Sam?" The word knife sliced through the fog still covering his brain. Sam tensed.

"What? What knife?" Did his voice sound too shaky? Sam thought it did. Dean just sent him a look that was exasperated and incredulous at the same time.

"What knife? The knife, of course. The demon knife! It's not in the weapon bag."

The accusing tone should have made Sam angry that his brother immediately suspected him of somehow taking it. The guilt that Dean was right, though, squeezed around his heart and Sam had to look away.

"I don't know. It must've gotten mixed up." Sam pretended to look around for a moment, before he got up and retrieved it from his clothes backpack. He was sure he'd stuffed it into the right bag yesterday, but then again, he wasn't exactly focused on that.

"There it is. I'm sorry, I must've put it in my bag when cleaning the weapons yesterday." Sam handed the knife over to Dean.

"But I saw you put it… Are you okay, Sam?" The question made Sam fight the tears that sprung to his eyes. His brother always asked him that. But now… The uncaring tone, the emotional coldness, the suggestion that caring for him annoyed Dean, was more like a burden to him… Dean just said that out of habit. He didn't really care if Sam was okay or not, he only played his part in the elaborate little make-belief they lived in right now.

"Yeah, fine." Sam turned around abruptly and started packing his own bag. He couldn't face Dean at the moment. Not when he was so close to breaking. He also made a mental note to be more careful with his nightly escapades. A lot more careful.

During his teenage phase of… alternative coping measures, neither his Dad nor his brother ever found out about this particular secret. Sam had been obnoxiously secretive until he'd gotten the hang of it. Some more practice and he'd be back in his old routine.

That made another cold shiver run down his back. He was already thinking about the next time…

"So, where are we going, anyway?" Sam asked Dean, trying to distract himself.

"Huh?" Sam finally turned around, facing his brother.

"Where we going, Dean?" Sam repeated, slightly confused. It wasn't like Dean to be so distracted around him lately.

"Oh. I thought… I thought we could go to the bunker for some time. Y'know, recharging and all that." Dean fumbled absentmindedly on handle of the knife Sam had just given him.

Sam's eyebrows rose and his eyes widened.

"To the bunker? Right now? Aren't we supposed to hunt something?

Dean straightened up and stacked the knife in the weapons bag with a little more force than required.

"And what, exactly, do you wanna hunt right now, huh? You take a year off without any particular reason and then you suddenly decide you can't live without it?"

It was a low blow and it made Sam shut up and lose his train of thought instantly. Any argument he might have had got stuck in his throat when he opened his mouth to speak. His muscles locked up, his fists clenched with this nails digging into his flesh.

Dean stared him down, then went on packing their bags.

Sam was frozen in place for a minute, watching Dean roughly handling the bags and avoiding his gaze.

Breaking his trance, Sam took his bag and quickly stalked to the door, wrenching it open and pulling it closed behind himself.

He practically ran to the Impala and dumped the bag beside the car, making his way to a little patch of grass in front of the parking lot. There, Sam paced up and down while running a shaky hand through his hair.

He couldn't believe his brother would still throw that at him. Furthermore, he couldn't believe he was still this affected by it. It's not as if Dean tried very hard to hide his contempt for Sam. Frustrated with himself, he kicked hard at a nearby trash can until it fell over. When that didn't help, he put his hands in his hair again and pulled at the strands.

And now, he'd just stormed out. Great. Like Dean needed any more reasons to think him untrustworthy or downright insane.

Panting for breath and trying to see through the burn in his eyes, Sam put his right hand against the gauze he knew was under the sleeve of his shirt and pressed on it. The white-hot blaze that spread from his left arm, cut into his brain and shut out the thoughts that screamed at him.

Keeping his hand clenched around the wounds he'd inflicted yesterday, Sam took deep breaths and determinedly walked back to the Impala. He swallowed convulsively to get the burn out of his eyes. He would not give his brother the satisfaction of seeing him cry. Sam knew he deserved the rough and cold treatment he got but any more humiliation and guilt and he knew he'd break from it.

If he needed any more help breaking, that is.

Because Dean had the car keys and the doors were locked, Sam leant against the passenger side, trying to act indifferent to what had just gone down. Only a few minutes later, Dean emerged from the roadside motel and silently got into the car. Even though the heat and the anger from before seemed to have vanished, Sam knew they weren't buried particularly deep, so he cautiously slid in the passenger seat. Letting his hair fall into his eyes, he turned his head away from his former lover, curling against the door that was exactly as rigid and unforgiving as Dean was with him.

Not wanting to watch the landscape pass as they drove and involuntarily be reminded of all the happy times they'd spent in this car, Sam closed his eyes and concentrated on the leftover sting from his wounds, thinking over where he'd gone wrong to ruin their relationship so completely.

WYDK

When Sam awoke it was dark outside. They were still on the road somewhere like they almost always were, but this time they knew the destination. Since the last hunt was pretty far away from the bunker, Sam figured it would be another 5 or 6 hours drive and his brother looked exhausted behind the steering wheel. So Sam spoke up, even though he knew that was the wrong thing to do. He didn't want Dean to think he didn't care. Because he did. More than he should, seeing how things were between them right now.

"Do you want me to take over for a little while? You look really tired."

"What? NO! No, Sam, just go back to sleep. I'm fine." It was a typical big brother thing to say, but Sam could feel there was more to it.

"Dean, I'm not going to crash the car while you're asleep. I haven't forgotten how to drive, y'know."

Dean whipped his head to the side to look at him. His eyes narrowed and his posture became tense.

"I'm driving and that's that. I think as we've established when I was in Purgatory, I can take care of myself just fine. So either go back to sleep or at least shut up!"

Sam took a moment to let it sink in and waited for the cold ache to spread through his stomach. As always when Dean brought up Purgatory and the way Sam let him down, all the fight went out of him along with pretty much all leftover hope that Dean could get past this and they could at least go back being brothers. Even if their relationship was too far gone to repair…

Sam turned his head away from Dean in slow motion. His brain was just so hazy with all the guilt.

He closed his eyes and hid the tears that fell behind his hair. Taking deep breaths as evenly as he could with shaky tremors rocking his body, he pretended to go back to sleep. And, because he didn't have anything else to do, after a while he did for real.

The next time Sam came to, he was still pressed against the right side of the car but something was amiss. With a startled jolt he woke the rest of the way up when he noticed that the engine was off and Dean wasn't in the car with him.

Wrenching the door open, Sam stumbled out of the Impala, standing on weak legs that had been crammed up for too long.

Panic creeping in, Sam whipped his head around to make sense of what was going on. Had Dean been taken by something while he was asleep and hadn't even noticed?

When his sight finally really took in his surroundings Sam found himself in front of the bunker and the panic ebbed a little. Despite the now familiar location, he found himself worrying.

How long had they been here? Why hadn't Dean woken him when they'd arrived? It was dangerous to just sleep in the car with the door unlocked on the side of the road, even if it was in the middle of nowhere.

Dean was well aware of that, he was the one who'd drilled it into Sam after all. Sam's heart clenched and his blood seemed to go cold before white-hot humiliation shot through his veins. Of course Dean let you sleep, idiot. He doesn't care about you, anymore. He'd probably be glad if something happened and he'd finally be rid of you.

Sam felt even weaker when his vision blurred as tears clouded his eyes again. He seemed to be doing that a lot lately.

Trembling slightly, Sam got his bag out of the car and took the keys from the ignition to lock it up and step inside the bunker. Now more or less expecting it, Sam let himself into the unlocked underground building and hesitated on the top of the stairs.

He could go looking for Dean and confront him about leaving him exposed like that in the car. But then, Sam figured he had no right to accuse Dean of something he'd done more than a lot of. The whole time without his soul, the time Dean spent in Purgatory…. He'd done his fair share of leaving his brother on his own.

Even more weary than after their last hunt, Sam just wanted to curl up and hide somewhere for a while. As quietly as he could, he walked to his room, the one he'd chosen the last time they were here. It wasn't really his. There was nothing there that would make it his, but Sam didn't want to get philosophical now, not when he was this drained.

So, instead, he lay down on the bed, pulled the covers over his head and cried until hiccups shook his body. After that, he just let his mind wander, much too tired to even think about getting up to get food for his rumbling stomach and beyond frustrated that he still missed a warm body next to his in his bed.

He couldn't really sleep, as he'd already spent the whole drive asleep, but Sam was glad that he lost track of time and neither his brain nor his brother cared to interrupt his wallowing.

When the emptiness in his stomach finally seemed too much to take and his muscled had frozen in the position they had been forced into, Sam got up and quietly made himself a sandwich. He was not particularly fond of the idea of running into Dean again this soon.

Sam locked the door after he'd let himself out. The cooler night air was refreshing on his skin and he took a deep breath, forcing his brain to quiet down.

They'd not been to the bunker often, so he was unfamiliar with its surroundings but he simply chose a direction and walked into the woods towards the back of the slight incline.

It was really dark outside. He stumbled through the woods, careful not to run into too many trees and to keep walking straight ahead so he'd have no trouble finding his way back.

When his feet started aching, he sat down on a hill in a slight clearing and stared unseeingly into the night sky. Flashes of memories passed in his mind and this time, he let them. Let the blur of smiles and jokes and laughter and love run over him and show him just what he'd lost.

It wasn't even the blind faith he missed most of all. Sam had criticized Dean more than once for having this kind of faith, even though he'd admittedly been talking about their Dad.

Most of all, he missed the casual little touches, accidental brushes of skin or not so accidental kisses, reassuring and soft or heated and filled with desire and love.

He desperately wished Dean would let him close again, wouldn't shy away whenever he was forced to be near to Sam. Feeling detached from his body, he watched the sky get lighter and turn to a pale greyish blue and then finally watched the sky erupt in flames as the sun rose.

Surprised that Dean hadn't yet shown up to remind him of what a failure he was, Sam didn't want to push his luck and started on his way back to the bunker, which took him considerably less time in the morning light than at night in the dark.

When he was standing on top of the metal stairs again, he spotted his brother sitting at the table, hunched over nursing a glass with something that looked decidedly like alcohol to Sam.

He didn't bother to comment on it, though. He only now noticed how cold he actually was with little shivers making his knees shake and his hands unstable. Sam wanted to escape to the shower quickly to warm up and then get back to this intricate act they were playing.

He half-expected Dean to go right in ignoring him. He even flinched a little as Dean spoke.

"Where have you been?" The quiet tone was dejected, soft and Dean didn't even look at Sam when he said it. The underlying hurt had Sam lowering his eyes to the floor nonetheless.

"I was just outside. Y'know, taking a walk, clearing my head. Girly stuff." Sam had hoped that the last part would signal Dean that it was time to start acting the part of their old selves again. He cautiously went down the stairs to stand still on the bottom, not knowing what to do next.

Dean didn't seem to be fazed by Sam's comment . He looked up from his position and fixed Sam with a hard look.

"The whole night? Just like that?" Dean asked incredulously, as if he thought Sam was making fun of him.

"Sam, if you need time to go meet up with your old girlfriends or whoever, just tell me! I don' t care but don't lie to me!"

The angry, loud tone and Dean's expression made Sam's posture go rigid in second, expecting an explosion like that to escalate in violence.

"I'm not lying." Sam hated the way his voice seemed to echo with the shakes of cold still passing though him. "I told you I went for a walk and that' exactly what I did." He was careful to keep the wording to the point but not accusing and the tone quiet but detached.

It didn't seem to matter, anyway. Before he had time to blink, his brother had him pressed against the nearest wall, fists clenched around chunks of his shirt and one elbow pressing against his throat.

"You want to keep your distance? Watch out for yourself only like you did while I was gone? Fine. But take off like that again and I will find you so I can kill you myself." Dean hissed out through clenched teeth with the muscles in his jaw working tightly.

Sam wouldn't have noticed, anyway. I will find you. Bloodstained sheets. I will find you. Metal handcuffs digging into his wrists, drawing blood.

I will find you.

Sam felt dizzy. His head was spinning while he was fighting for consciousness. He couldn't breathe.

I will find you. He was panting, he was sure of it, but there wasn't enough air… He was choking and there was a ringing in his ears.

"Sam? You hear me? Sam!" Dean felt the anger go out like a flame doused with water. Concern and panic were running up on him now. He'd made sure not to press on Sam's throat too tightly. He hadn't wanted to hurt him! But, apparently, he had.

"Sam! What is it? What's wrong? C'mon, breathe!"

Sam felt the weight around his throat ease up but he was too far gone. He was hyperventilating and focused on not throwing up.

"SAM! Dammit. Snap out of it!" Sam came back with a jolt and froze completely when the burn of the slap across his cheek pulled him out of his panic attack.

His chest was heaving with the forced lungfuls of air he sucked in.

When Dean stepped back to give him more room to move but laid a hand on his shoulder that was surely meant to be steadying and reassuring, Sam shrugged out of the way and backed up against the opposite wall.

"Don't touch me!"

"Okay, okay. I won't touch you." Dean held up his hands and stayed where he was to make himself as non-threatening as possible. He needed to find out what just happened, because the shock of seeing his little brother suffocating for no reason made him shakier than he wanted to admit.

"What happened, Sam?" When he didn't get more than another panicked look and a frantic jerk of Sam's head, he pressed on.

"What was it? Did I hurt you? God, I didn't mean to, I swear."

When Sam's back hit the wall, he felt trapped again. He was still unstable and... I will find you.

No, he couldn't think about that now. He had to get away, had to get room to breather properly and calm down.

That his brother was the one who'd triggered it, even accidentally, and had slapped him… On top of everything else, it was just too much.

"Well, you did, okay?! Now leave me alone, unless you want to throw me around some more!"

Sam didn't wait for a reply, instead he turned and ran to his room, slamming the door behind him. For the first time since they were back on the road together, Sam locked his brother out of the room.