Welcome to my first serious fic! I hope you enjoy it, if you enjoy this kind of thing. I have never written anything like this before and I hope it turned out okay.
This was requested by Calcifer. I hope you like it, Callie!

It was the pungent smell of being in a sewer that jarred Sam Winchester back to his senses. His head felt heavy and a sharp pain radiated from the back of his skull making the world around him fuzzy and out of focus. The hunter groaned at the way everything seemed to hurt while he tried to remember how he had gotten into this situation. Nothing came to mind.

He needed to focus on what his priorities were before anything else. Concentrating harder than he thought he would need to, he came up with a plan. He needed to find his brother and come up with another plan to track down the shapeshifter that was currently running around town wearing Dean's face. First, he needed to get up. Trying to move from his sitting position, ignoring the way his limbs were growing numb, he discovered he was bound to a pillar. Trying to move his arms, he found them bound together with rope. Looking around, he found his ankles were in the same position: bound with rope. Judging by the way he was unable to move, he guessed his chest was the tied to the pillar as well though he wasn't sure, he couldn't feel it.

Struggling, in attempt to loosen his bonds, made his vision turn grey around the edges. He could feel the coarse fibers cutting into the flesh of his wrists, drawing blood. The hunter leaned his head back, resting it on the pillar he was attached to. When his vision began to swim, he decided he should probably close his eyes until the world stopped moving. As soon as his eyelids came together, he heard it. The sound of boots walking through puddles of water and sludge. There was something about the lope, as if the walker was slightly bowlegged...

"Dean!" Sam called out, his voice cracking at the effort.

"Sam!" Dean's voice called back, the sound of his boots getting louder and faster as they grew closer. The captive hunter felt himself relax knowing his brother was on his way to get him out of this situation. "Sam, there you are." There was something in the man's voice that betrayed something. Sam knew it was not his brother, Dean would never sound so easy about his brother being kidnapped.

The other man walked around the pillar to face his prisoner, a smirk on his face. Sam groaned. "What's the matter, Sammy?" The fake Dean drawled. "Not excited to see your brother?" He reached out to touch the other man's face but Sam turned it as far as he could to the side, baring his teeth.

"You're not my brother." Sam snarled, spit flying.

The man before him chuckled. "No," he agreed, pulling a large Bowie knife out from behind him and tapping it thoughtfully against his chin. "I'm better. All of the fucked up memories with no need to hold anything back from you." His smile widened. Sam glared at him, breathing deeply, trying to keep himself from having a panic attack as the imposter brought his face mere inches from the hunters. "Oh, Sammy. If you only knew what I knew." He let out a laugh, shaking his head. "How you would... Squirm." He whispered the last word in the man's ear, his lips grazing the shell.

"Shut up!" The hunter spat.

"Don't you want to know all of your brother's secrets." The fake Dean asked, pulling back slightly to look into Sam's eyes. Sam tried to look anywhere else, anywhere other than the familiar green that promised Sam would not like what he heard. "You're brother is pretty fucked up when it comes to you." The shifter reached out, grabbing his captive by the face and forcing him to look him in the face. "If you had any idea about what I know, you would run for the hills and never look back."

"Shut up! Just shut up!" Sam snarled, wrenching his face out of the other man's hand.

"No, Sam. Listen to me." The imposter growled, grabbing a fistful of Sam's long hair, bringing their faces close once more. "He wants you." He laughed. "If you only knew how many times he thinks about you in a sexual way a day you would want to vomit. He fantasizes about you. Dreams of the things he would do to you if you would let him." He licked his lips before letting go of the man's hair, pushing his head to the side as he did it.

"You're lieing." Sam groaned, his vision going grey. The shifter ran his thumb along the blade of the Bowie.

"Believe whatever you want to but the truth is staring you in the face." He gently placed the tip of the blade against Sam's cheek, not enough pressure to cut in but the threat was there. "He wants you, Sam." A wicked smile played along his features, a look he had never seen on his brother's face. "And his feelings are strong. If he is too much of a coward to act on them, I don't see why I shouldn't."

"Don't touch me." Sam growled, his vision going grey. The smile disappeared off of the shifter's face.

He reached around to the back of Sam's head, grabbing another fistful of hair, bringing their faces close once more, not caring that the blade cut into the bound man. "I will do whatever I want. What are you going to do about it?" He raked his eyes down the injured man's form and Sam closed his eyes. He couldn't see that predatory look in his brother's eyes. Dean's eyes.

"Please. Don't." Sam pleaded. Was it just him or did his voice sound faint? With the monster wearing his brother's face Sam felt helpless. Worse, he felt hopeless that Dean would be able to come to his rescue in time.

When he opened his eyes again, the shifter was staring at Sam's lips, his hand still in Sam's hair. "Why should I stop? I want this." The hunter tried to pull away, but fake Dean got a tighter grip on his hair and pushed the tip of the blade down Sam's cheek, drawing a line of blood making him grimace. Knowing he could not pull away, the shifter pressed a kiss to the hunter's mouth.

As expected, Sam resisted. He ground his teeth together, ignoring the way black spots danced before his vision. "Come on, Sam. You can either participate, or," he took the blade and ran it down the man's shirt, cutting it open along with his chest. "Things could get a little rough and I can guarantee you will not like it." He laughed at the way Sam gasped at the pain.

"Never." Sam squeezed his eyes shut again.

"Alright but remember, you asked for it." The shifter smashed his mouth into Sam's ripping at the tender flesh with his teeth, drawing more blood as he pulled at the man's lips. Dropping the blade, fake Dean busied his hands with Sam's belt. Growing impatient, he picked the blade back up and ripped into Sam's jeans, cutting the fabric away not caring how many times he cut into the man's flesh. Relishing in the way he cried out.

It was when the shifter stood up to undo his own belt, Sam made his decision. He couldn't go through with this, especially at the hand of his brother, he did the only thing he could. Taking advantage of his already fuzzy head, and bashed it into the pillar behind him as hard as he could, successfully knocking himself out.

...

Dean rushed through the tunnels of the sewer, hoping he was going the right way. He had gotten lost originally and hoped he was not too late. He feared something was happening to his brother and he was not going to be there to stop it. When he found his brother, he stopped in his tracks, his blood turned to ice in his veins. It was worse than he had imagined.

The shifter, wearing his face, was riding his brother who seemed to be unconscious and tied to a pillar. Dean's vision turned red. The son of a bitch that had taken his identity, hurt Sam's friend Becky, and kidnapped his brother was now raping him.

Not thinking, Dean pulled his favorite pistol out of his jeans and took aim at the shifter. Hoping he did not get Sam, he took his shot, getting him in the leg first. The shifter looked his way, cursing, and he took another shot. Right in the head. Running to where his brother was sitting unconscious, now covered in the shifter's blood as well as his own, Dean unloaded the rest of his clip into the dead body before kicking it out of the way.

Placing the gun back into his jeans, he crouched before his brother. He checked that he was not going to bleed out, checked his breathing and that he had a pulse before grabbing his doppelgänger and dragging him out of the room. He needed to find somewhere to hide the body before he could tend to his brother's wounds. He found a tunnel that had collapsed at some point in time and decided it was the perfect place to hide the body. He dragged it in as far as he was able to before covering it in rubble. He knew somebody was bound to find it but he hoped he and Sam would be out of town by then. when he was satisfied with his work, he made his way back to his brother.

On his way back to Sam Dean couldn't help but think of all of the ways this could break his brother. What if he did not know it was a shapeshifter? What if Sam had been awake for most of it? The more he thought about it, the worse Dean felt about it. He should have been there to protect him. By time he got back guilt was eating away at him. A poison that shook him to the core.

It was his fault. He had made a mistake when he was tracking the thing down and had gotten lost in the had been his fault for not listening to Sam when he told him he knew where he was going and look at what had happened.

The room was quiet. The only sound came from his boots as he walked through puddles of who knew what on his way to his little brother who was beginning to wake up. He kneeled before Sam, who was covered in blood and sludge.

"Sammy, hey Sam. Wake up, okay? I'm going to get you out of here." Dean told the semi unconscious man while he worked on cutting the ropes away from his ankles. When that was done, he moved his way to the ropes around his chest and wrists, all the while telling him that he was going to patch him up when they get out of there and that his brother was there to take care of him.

"Dean?" Sam asked, beginning to lean to the side.

"I'm here, Sammy." He grabbed the taller man by the shoulders to steady him but Sam flinched at the touch. "The shifter's dead, he can't hurt you anymore."

"How do I know you are really Dean?" Sam asked, his eyes rolling in their sockets.

"Because I would never hurt you."

It took a lot of time and a lot of effort to get Sam out of the sewer tunnels. When they made it to the surface, Dean made the decision to call an ambulance for his brother. He was worried that Sam could have a concussion or worse. Not wanting to risk it, he laid Sam down in an ally and made an anonymous 911 call. With a warrant out, Dean couldn't be caught taking him to a hospital. After the medics came and took Sam away, Dean went to the next town over to await the call to come for his brother. He waited two long and agonizing days.

In the Impala, on their way out of town, Dean decided to ask the question that had been hanging over his head since the sewer. He cleared his throat. "Hey Sam?"

Sam had been staring out the window, watching the buildings move past him on their way toward farmland. "Yeah?"

"What happened in the sewer?" He glanced at his brother for a moment before giving his attention back to the road before him.

Sam rubbed the back of his neck with one hand. "He, uh, told me that you wanted me and that he might as well take what you wanted." His face turned pink, not that Dean saw.

He, he cut you up pretty good." Dean observed, clutching the steering wheel tighter than he needed to.

"Yeah, that was for not participating." He was glad he was not facing his brother, he did not want Dean to see the tear that had escaped. Another long moment passed between them.

"How much do you remember?" Dean pushed, not because he wanted to but because he needed his brother to understand he was there for him. That the ordeal with the shifter was over.

"Not much, he was undoing his pants when I knocked myself out. There was no way I could go trough with it and there was no way I could stop it. I figured I didn't have to be conscious for it." He hated the way his voice broke.

"I'm so sorry, Sammy." Dean wanted to reach out, to comfort his little brother but he did not think his brother was ready for that. Instead, he gripped the steering wheel until his knuckles turned white.

"Dean," Sam asked, not turning away from the window.

"Yeah?"

Sam swallowed hard, not wanting to ask the question that kept bubbling to the surface but knew he had to. ""Was the shifter right? Do you want me?"

Dean shifted slightly in his seat, licking at his lip. "That doesn't matter, Sammy. What matters is that I love you and I will never do anything that you don't want."

"That doesn't answer my question." Sam pushed.

Dean let out a sigh. "Yeah, I do, but that doesn't mean anything unless your comfortable with it." Sam nodded, he was not ready for anything like that. Maybe one day but not today.

And they were okay with that.