This is an old story I finished years ago but never posted. Written after s04e10.

Title from "Bring Me Simple Men," by Timber Timbre.

It took him a few days, but he caught on. He might not have been the sharpest tool in the shed, but he was smart enough. Nobody could hide things too long from Dean. He'd suss it out sooner or later, hunter's instinct bred into his DNA. Sam was no different than anyone else Dean observed, especially when it came to Ruby.

He could hear the way her name sounded on Sam's lips. It sounded different than before - before, it was hard and bitten off, an anathema on Sam's tongue. Now, the syllables were soft and rounded. Sam took great care in saying her name. Ruby seemed to know that her name was safe in his mouth.

And Dean could see the way she looked at him with those big, adoring cow eyes of hers. Like the only thing she could see was Sam. It was all so familiar that Dean felt sick just watching it unfold.

Ruby just fit so easily into all the places that used to be Dean's. So effortlessly. The realization made his stomach do little flips. He'd tighten his hand around his beer bottle as Ruby and Sam plowed through hamburgers and fries, and she'd toss her head back and lick the ketchup from her fingers. She'd catch Sam watching and she'd take extra care to lick up every last drop of red. Dean would sit back, sink even further back into the shadows, and work on his already lukewarm beer.

Their connection was so easy, that Dean could almost forget he'd once been in Ruby's place. He'd once been Sam's only companion.

Now, Sam had no need for him. All the times Sam would have looked to Dean, he now looked to Ruby. She'd smirk, toss off a remark (that Dean mouthed silently along with her, second nature) and Sam would laugh. His eyes would crinkle and his cheeks would dimple, and Dean would burn.

[][][][][]

"Dean, awaken."

Dean didn't bother to open his eyes. He knew who the voice belonged to. He just rolled onto his stomach and pushed his face into his pillow.

"What is it, Cas," he mumbled, barely audible. Dean rubbed his fists against his eyes. "Don't you ever knock?"

Castiel put a solid, cool hand on his shoulder blade. "You were - dreaming," Castiel said. "It was not a nightmare, but it was not pleasant either."

"Didn't I tell you to get outta my dreams?" Dean asked, raising his head. He wrapped his arms around the pillow, keeping it as a barrier between himself and the angel. He still didn't know what Castiel's deal was. Besides watching people while they slept and occasionally jumping into their dreams.

"You did," Castiel said, lowering his head. Not in shame, though. Something else, Dean just couldn't place it. Sometimes he hated this enigmatic bastard with the fire of a million suns. "You were dreaming about Sam."

Dean tightened the motel pillow to his chest. "Was not," he said, but it was useless. Castiel could see into his freaking dreams, of course he'd know if Dean was lying about them. "Okay. Maybe I was. Doesn't give you any right to -"

Castiel raised his head again. His eyes were an electric shock of blue. "But it was unpleasant."

Dean recalled flashes here and there - the curve of Sam's smile, although it hadn't been a kind one. The crisp green of his eyes right before they shuttered, like a lizard's, into inky black. He tried to latch onto it, grab hold of the rest of the dream, but it slipped from his tenuous grasp like a handful of sand.

"That why you wiped it outta my head then?" Dean muttered, still wrapped around the pillow.

He felt like a child, ridiculous and weak. He thumped the pillow to the mattress and crossed his arms over his chest.

"I do not want you to be in pain," Castiel said.

"Okay then. Well, neither do I. At least we're on the same page there," Dean said. "So -" He glanced over to Sam's bed, which was empty. " 's he sneakin' 'round with Ruby?" Dean nodded to the angel for an answer.

Castiel averted his gaze. "Your brother and his companion have gone out for - a midnight snack."

"Midnight snack," Dean said, whistling, raising his eyebrows. "Ain't lyin' a sin?"

"It is not quite a lie." Castiel stood and slid his hands into the pockets of his tan coat.

Well, to put it more accurately, the coat of the poor bastard Castiel was wearing. It was just easier to think of everything Castiel wore as his.

"Huh." Dean frowned.

"Sam - does not mean to cause you pain," Castiel said.

Dean snorted and crawled back under the covers. "Whatever. He's happy, that's all that matters." Dean punched up the pillow, maybe a little too enthusiastically.

"Goodnight, Dean. Sleep well."

There was the soft fluttering of wings and when Dean looked up, the angel was gone.

[][][][]

Dean was half asleep, clinging to his pillow, semi-conscious, when the floorboards creaked. He cracked open an eye to see Sam shut the door behind himself and adjust the front of his shirt before creeping over to the beds.

Dean sat up and snapped on the bedside light. "Where've you been?" Dean asked.

Sam stopped dead in his tracks, deer-in-headlights look frozen on his face. "I thought you were sleeping," he said, after a couple minutes of awkward silence.

"Couldn't get to sleep," Dean said. It was partly the truth. "Where've you been," he repeated.

Sam sunk deeply into his motel bed and shut his eyes. He rested his hands over his chest, as if he were trying to keep his heart from leaping out. "Out with Ruby," Sam said. His words were slow and staggered; he was drunk.

Dean sat upright in bed and rubbed his fists over his face. "Cas said you two went out for a midnight snack." Dean didn't mean to sound so damn jealous of the relationship his brother and his demon - whore, concubine, companion, whatever the Hell she was to him these days - had. It just kind of came out that way on its own.

"The fuck is your problem?" Sam flared, muscles tensing.

Dean wondered if Sam would fight him to protect Ruby's honor. He wondered how far he could push until Sam made a choice. "I don't have any problems," Dean said.

"Stop being so fucking hostile. Ruby saved my life -"

"She's a demon," Dean interrupted. "She's using you."

He really had no idea why he was bringing this all up again. They'd gone over it before, albeit briefly; Sam described, in excruciating detail, fucking Ruby for the first time, right down to how she didn't wear a bra, how he could feel her heat through her jeans, how she reminded Sam of - and that was when Dean made Sam stop, change topics. Brain-stabbing imagery indeed.

Sam groaned. "Jesus, not this again."

"And you're in love with her," Dean spit, like a curse.

"I - what?" Sam stared at him, blinking back shock.

"You're in love with her. I can see it. Hell, astronauts could probably see it from space," Dean quipped.

Sam shook his head, laughing brittlely, pinching his fingers over the bridge of his nose. "Whatever, Dean. What-the-fuck-ever. I'm too tired for this fight."

"- it's not a bad thing," Dean ventured, with cautious, tiny steps. "If you're happy."

"I'm not in fucking love with Ruby!" Sam exploded.

"Someone's just a little bit defensive." Dean crossed his arms over his chest.

Sam stomped over to his bed and leaned down, yanking violently at the comforter. "I'm not fucking defensive. I just don't want to have this fightagain," Sam snapped. He threw himself into bed and jerked the covers up to his armpits. "Drop it, Dean."

Dean settled on the end of his bed, casting a glance Sam's way. "Just answer me one thing and then I'll drop it," Dean said.

Sam rolled over, turning his back to Dean. "Go to sleep."

"Just tell me if you're happy," Dean said, hating how desperate and small he sounded. He knotted his hands in the bedspread and tugged.

Sam rolled back over and stared at the ceiling, huffing. "You're not gonna get off my ass until I answer you, are you?"

"Nope," Dean said.

Sam sighed wearily and rubbed his hands over his face. "I - I don't know. I haven't been happy in so long. But this feels like it, you know? This feels like it could become something. Like - something good."

Dean sighed. "You'll let me know the moment it isn't, right?"

He didn't expect that Sam would, knew that whatever came out of Sam's mouth would be a lie, but he needed the reassurance anyway.

"Of course I will," Sam said.

" 'kay, Sammy," Dean said turning onto his stomach and pushing his face into his pillow. "That's all I needed to hear."

Sam hummed tunelessly. "All right, Dean. Uh, goodnight," he said.

"G'night."

Dean floated into a sea of dark dreams that he wouldn't remember in the morning.