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Green‑Eyed Jealousy

Summary:

When he introduces his quiet, sharp-eyed best friend to his little brother Sam, he doesn’t expect Sam to light up every time Cas is in the room—or for Cas to find it so amusing. What starts as a harmless crush spirals into awkward tension, unexpected jealousy, and Dean finally being forced to face what everyone else already knows: he’s in love with Cas

Notes:

Prolly not

(See the end of the work for more notes.)

Chapter Text

Dean Winchester was nervous.

Which was ridiculous, because Dean never got nervous. He was captain of the wrestling team, had a reputation for not giving a damn, and could sweet-talk his way into or out of anything—including Principal Meyers’ office three times last semester. But now?

Now, he was sweating bullets because he was walking Castiel Novak into his house.

The house wasn’t even the problem. It was Sam.

Dean loved his little brother, but he was also a walking question mark when it came to people. Too curious, too clever, and way too observant for Dean’s liking.

And Cas? Cas was… well, Cas.

Bright blue eyes, tousled hair, always smelled like old books and spearmint gum. Soft-spoken. Freakishly smart. Somehow didn’t care about being popular, and yet everyone remembered him after one conversation. Dean had met him in sophomore year when they were paired up in Bio, and now—somehow—they were close enough that Cas felt like the one person who saw through all his bullshit.

Which made introducing him to Sam kind of a big deal.

Dean pushed open the front door. “Sam! We’re here!”

Sam looked up from the kitchen table, where he was surrounded by open textbooks and half a peanut butter sandwich.

“Hey!” he said, pushing his hair out of his eyes. Then his gaze landed on Castiel.

There was a beat. Then another.

“Oh. Uh. Hi.”

Dean snorted. “Sam, this is Castiel. Cas, meet my brother, Sam. Resident brainiac. Lives off protein bars and anxiety.”

Castiel stepped forward, extending a hand politely. “It’s nice to finally meet you, Sam. Dean mentions you often.”

Sam blinked a few times, then grinned awkwardly as he shook Cas’s hand. “Really? Uh—that’s cool. Nice to meet you too. Your voice is like, uh… really deep.”

Dean nearly choked.

Castiel tilted his head, a tiny smile tugging at his lips. “I’ve been told that before.”

Sam looked ready to evaporate. “Sorry, that was weird, I didn’t mean it like—okay, I’ll just, um—homework!”

Dean dragged a hand down his face. “God, you’re such a dork.”

A few days later, the two of them were holed up in Dean’s room, sitting side-by-side on his bed as they scrolled through dumb YouTube videos. Dean glanced at Cas out of the corner of his eye.

“You know Sam keeps asking about you?”

Cas didn’t look away from the screen. “Hmm?”

Dean shifted. “He texted me yesterday asking if you liked Star Trek or Star Wars more. The day before that it was, ‘what’s Cas’s favorite book.’ I swear, I should start charging him.”

Cas finally looked at him, eyes twinkling. “I think it’s sweet.”

Dean made a face. “It’s weird.”

“It’s harmless,” Cas said, nudging Dean gently with his elbow. “He’s young. And I’m flattered.”

Dean crossed his arms, scowling. “You better not be encouraging him.”

Castiel gave him a long look. “Are you… jealous?”

Dean scoffed. “Of my brother?”

Cas said nothing, just tilted his head in that way that always made Dean feel like he was being scanned by some alien truth-ray.

Dean muttered, “Okay, maybe a little. But not in a gross way. Just in a ‘you’re my friend and I don’t like sharing’ kind of way.”

Cas raised an eyebrow. “Your friend?”

Dean went quiet.

Cas leaned in, voice gentler now. “Dean.”

Dean stared at the ceiling. “You know what I mean.”

Cas hesitated. Then slowly, softly, he said, “Yeah. I do.”

And Dean looked at him—and for a second, just a second, everything felt easy.

Sam had that look in his eyes again.

Dean noticed it as soon as he walked into the kitchen Saturday morning—Sam hunched over his phone, chewing the end of a pen, trying not to smile like an idiot.

Dean dropped a box of cereal on the counter. “What’s with the face?”

Sam looked up too quickly. “Nothing! Just… homework.”

Dean raised an eyebrow. “Homework makes you smile now?”

Sam didn’t answer. He casually put his phone down, but not before Dean caught the contact name glowing on the screen: Castiel N.

Dean froze mid-pour. “Why are you texting Cas?”

Sam shrugged too casually. “I was just asking if he’s going to the Spring Fling next weekend.”

Dean blinked. “You—you invited Cas to Spring Fling? Why?”

Sam tilted his head like Dean had asked a dumb question. “Because he’s cool? And it’s not really a date or anything. I just thought it’d be nice if he came.”

Dean scoffed. “Cas doesn’t even like dances. He thinks they’re ‘overstimulating social rituals driven by outdated courting practices.’ His words.”

Sam grinned. “Yeah, he said that. But then he said he’d come if you were going.”

Dean choked on his cereal.

“Excuse me?”

Sam leaned on the counter with a suspiciously innocent look. “So, you are going, right?”

Dean narrowed his eyes. “This is entrapment.”

“Maybe,” Sam said, already texting again. “But Cas said it sounded fun. And I think he’ll have a better time if you’re there too.”

Dean grumbled something under his breath but didn’t say no.

 

The school gym had been transformed—or at least, an attempt had been made. Twinkle lights draped from the ceiling, paper stars hung from basketball hoops, and the DJ was already blasting a mix of 2000s throwbacks and awkward slow songs.

Dean stood by the snack table, sipping cheap fruit punch and trying not to look like a third wheel.

Which was stupid, because he was the one Cas came with.

…Right?

Castiel was across the room, standing next to Sam by the banner-covered bleachers. Sam was laughing at something Cas said, blushing pink when Cas looked at him with that patient, focused gaze Dean knew too well. Sam was trying to act casual, but Dean caught the way he tugged at his too-long sleeves and glanced at Cas like he hung the freaking stars himself.

Dean’s jaw tightened.

He looked away, only for Cas to appear beside him moments later, holding two cups of punch.

“One for you,” Cas said, offering one to Dean. “And one for Sam, but he’s currently cornered by Madison and her very aggressive glitter perfume.”

Dean snorted and took the cup. “Thanks.”

Cas tilted his head, studying him. “You okay?”

“Fine,” Dean said a little too quickly. “Just… watching.”

Cas followed his gaze. Sam was laughing again, eyes shining.

“He really likes you, you know,” Dean muttered.

Cas blinked. “Sam?”

“Yeah.” Dean shifted awkwardly. “He thinks you’re cool. Smart. Mysterious. Probably has a little shrine with your name on it in his locker or something.”

Cas chuckled. “He’s sweet. I’m flattered.”

Dean gave him a sideways glance. “You keep saying that.”

“Because it’s true.”

There was a pause.

Then Cas added, voice lower, “But I didn’t come here for Sam.”

Dean’s breath hitched.

Cas looked him straight in the eye. “You know that, right?”

Dean opened his mouth—and was promptly interrupted by Sam, bounding over with a grin.

“I escaped the glitter bomb!” Sam said, beaming. “Cas, I was gonna ask—do you wanna check out the photo booth? I think they have props.”

Dean stepped back as Cas looked at him for a beat before turning to Sam. “Sure. Let me just finish this.”

As Cas and Sam headed toward the photo booth, Dean stood alone again, fuming internally while watching his best friend try on oversized heart-shaped sunglasses next to his starstruck little brother.

He drained his punch.

Wingman? More like wingcrush.

Monday morning hit like a truck.

Dean slammed his locker shut harder than necessary, earning a weird look from a passing freshman. He didn’t care. His mood had been in the gutter ever since the Spring Fling, and the image of Cas and Sam laughing in feather boas at the photo booth had taken up permanent residence in his brain.

It was just a dance. Just pictures. Just… Sam staring at Cas like he was a damn rom-com protagonist.

Dean was halfway to bio when Cas appeared beside him, walking in that calm, steady pace that never matched the chaos of the school hallways.

“Good morning, Dean,” Cas said.

Dean grunted something vaguely human.

Castiel didn’t press. He never did. He just walked beside Dean, quiet for a few beats before saying, “Sam texted me this morning. He said he found a copy of The Great Gatsby with all my favorite quotes marked.”

Dean nearly tripped over his own feet. “He’s giving you books now?”

Cas blinked. “He said it was a ‘thank you’ for coming to the dance.”

Dean stopped walking and faced Cas. “You know what he’s doing, right?”

Cas tilted his head. “He’s being kind.”

“He’s flirting, Cas.”

Cas’s brows furrowed slightly, like he was choosing his next words carefully. “He’s fifteen, Dean.”

“Exactly,” Dean muttered, pushing his fingers through his hair. “He’s fifteen, and he’s got hearts in his eyes every time you breathe near him.”

Cas paused, voice calm. “And why does that bother you?”

Dean opened his mouth—then shut it.

The hallway bustled around them, lockers slamming, students laughing, shoes squeaking on linoleum, but all Dean could focus on was Cas.

“It just… does,” he finally said, low.

Cas didn’t say anything. Just watched him. The silence stretched between them like a string pulled too tight.

“Look,” Dean muttered, “he’s a good kid. I just… I don’t like him getting ideas.”

“About me?” Cas asked, tilting his head.

Dean looked away. “About you. About… us. I don’t know.”

“Dean,” Cas said, voice gentle but firm, “I’ve known you for two years. I’ve only come over for you. I’ve sat through Star Wars marathons, listened to your terrible mixtapes, eaten your awful attempts at mac and cheese—and I’ve never once wondered why.”

Dean snorted softly. “They’re not that bad.”

“They’re inedible,” Cas said with a smile, and Dean’s stomach twisted with something fond and stupid and warm.

Then Cas’s smile softened. “I know Sam has a crush. And I think it’s kind of adorable. But it doesn’t mean anything.”

Dean’s chest tightened. “It means something to me.”

Cas blinked. “Why?”

Dean looked down at the scuffed tile floor. Then back up, his voice barely above a whisper.

“Because he sees you the way I do.”

Cas took a step closer. “Then tell me how you see me.”

Dean’s heart pounded. His mouth went dry. He was about to say something—something real—when the bell rang, jarring them back into the world of crowded halls and impending tardies.

Cas held Dean’s gaze for one more moment. Then he turned.

“I’ll see you after class,” he said softly.

And just like that, he was gone.

Dean stood frozen in the hall, his hands still clenched into fists at his sides, as the late bell echoed through the air.

Saturday afternoon rolled around crisp and quiet. Dean was on his way to meet Cas at the used bookshop downtown—one of those small, musty places where the shelves leaned like they were tired of standing and the owner always forgot what he’d already sold.

It wasn’t a date.

Not technically.

Cas had just mentioned the shop was running a sale on classic literature, and Dean, in a moment of weakness (or longing—whatever), had said, “Cool. I’ll go with you.”

No Sam. No school. Just them.

Dean walked into the shop, bell above the door chiming softly, and immediately spotted Cas at the back, crouched in front of a shelf with a paperback copy of Slaughterhouse-Five in his hand and that little furrow between his brows.

Dean’s stomach flipped in that annoying way it always did around Cas.

“Find anything weird and obscure?” Dean asked, walking over.

Cas looked up and smiled, that soft kind of smile he didn’t give just anyone. “Not yet. But I found something I think you’d like.”

Dean raised a brow. “Yeah?”

Cas held up a book titled Cars, Culture, and the American Dream. “It’s got a chapter on muscle cars. I thought of you.”

Dean laughed. “You’re such a nerd.”

Cas shrugged. “Takes one to appreciate one.”

They browsed for a while, voices low, laughter soft between dusty aisles. It felt… easy. Normal. Like the universe was holding its breath, waiting for Dean to stop being a coward and say something.

Then the doorbell chimed.

Dean turned—and his soul did a full-body sigh of despair.

“Hey!” Sam called out cheerfully, waving from the front of the store, backpack slung over his shoulder. “Cas texted me about the sale!”

Dean turned to Cas slowly.

Cas looked… innocent.

Too innocent.

“I may have mentioned it in passing,” Cas offered.

Dean glared. “In passing?”

“I didn’t think he’d show up,” Cas said, clearly lying.

Sam joined them with his usual energy, already holding up a copy of 1984. “I’ve been meaning to get this edition. And look, it even has annotations in the margins—Cas, you’ll love this.”

Dean clenched his jaw as Sam practically shoved the book into Cas’s hands and started rambling about Orwellian themes and dystopian metaphors. Cas humored him with that calm, patient attention he always gave, but it still made Dean’s skin crawl.

They wandered the store for another half-hour, but the easy rhythm Dean had shared with Cas was gone, thrown off by Sam’s constant questions and the way he hovered just a little too close.

Dean was over it.

“Hey,” he said finally, trying to sound casual. “Cas and I were gonna grab coffee after this. Just the two of us.”

Sam paused, caught off-guard. “Oh. I mean—I could come too.”

Dean offered a tight smile. “You could, but you’re not.”

Sam blinked, visibly surprised, but then he nodded. “Right. Yeah. I get it.”

Cas looked between them, eyes sharp, and said nothing.

Outside the shop, Dean and Cas walked side-by-side again, paper bags of books swinging at their sides. The sun was low, casting a golden haze over the sidewalk.

“So,” Dean said, voice a little stiff, “you invited him.”

Cas nodded. “I did.”

“Why?”

Cas looked over at him. “Because I wanted to see what you’d do.”

Dean stopped walking.

Cas stopped too.

Dean’s heartbeat picked up. “What’s that supposed to mean?”

Cas took a step closer. “Dean. You’ve been dancing around this for weeks. Months, maybe. I know you get jealous. I know you get frustrated. But I don’t know what you want.”

Dean swallowed hard. “I want…”

Cas waited.

Dean let out a shaky breath. “I want you. Just you.”

Cas stared at him, eyes impossibly blue in the sunlight.

And for a second, Dean swore Cas was going to kiss him.

He leaned in, barely a breath apart—

And Dean’s phone buzzed.

SAM: Found a café nearby! Wanna meet?

Dean closed his eyes.

Cas stepped back, not angry, not upset—just… patient.

“Another time,” he said softly, and turned away toward the street.

Dean watched him go, heart thudding, so close to everything he wanted and still not quite there

Dean avoided Cas for two whole days.

Which was impressive, considering they shared three classes and half a dozen friend groups. But Dean was nothing if not stubborn, and when faced with overwhelming feelings and the terrifying possibility of happiness, his first instinct was always to shut down.

So he ghosted.

No texts. No lunch table conversations. No “accidental” run-ins by his locker.

And Cas, true to form, didn’t chase him.

That only made it worse.

By Wednesday afternoon, Dean was wound so tight he nearly broke his locker trying to yank it open. The door groaned, swinging wide—and there, taped inside, was a sticky note written in Cas’s unmistakable handwriting.

“Green-eyed jealousy suits you. But honesty suits you better.”

Dean stared at it.

His stomach dropped.

He slammed the locker shut and turned on his heel.

He found Cas outside, under the big oak tree behind the school where they used to eat lunch on warm days before everything got complicated. Cas was leaning against the trunk, reading a battered copy of Paradise Lost, coat half-off his shoulders, hair ruffled by the wind like he didn’t even notice.

Dean stopped a few feet away. “You really left me a note?”

Cas looked up calmly. “You weren’t answering your phone.”

Dean exhaled, rough and low. “You trying to be poetic or something?”

“Would it work if I was?”

Dean’s lips twitched, but he forced himself to stay serious. “Why didn’t you push me?”

Cas closed the book gently. “Because I wanted you to come to me when you were ready.”

Dean took a step closer, then another.

“I’m not good at this,” he said.

Cas stood. “At feelings?”

“At… people. At telling the truth. At not being an idiot around you.”

Cas tilted his head, but there was a warmth in his expression now. “Then stop being an idiot.”

Dean hesitated. “Sam—”

“Is not a problem,” Cas said gently. “He’s a kid with a crush. And I’m an adult with choices. I chose you, Dean. I’ve been choosing you.”

Dean’s chest tightened.

Cas added, “I just need to know if you’re ever going to choose me back.”

Dean stepped forward, heart pounding so loud he could barely think. “Cas. I—God, I’m so in love with you it makes me crazy. And yeah, I get jealous. Of Sam. Of anyone. I’ve been trying to act cool about it but I suck at pretending, and the truth is, I don’t want anyone else looking at you the way I do.”

Cas’s expression didn’t change.

But his hand found Dean’s, fingers curling in slow and sure.

“That wasn’t so hard,” he murmured.

Dean huffed a laugh, eyes locked on him. “Kinda was.”

Cas leaned in. “But worth it?”

Dean nodded, and before he could say anything else, Cas kissed him.

It was soft—confident—but soft. Like something that had been waiting to happen for a long time. Like relief. Like an answer.

When they finally pulled apart, Dean grinned, breathless.

“Finally,” he muttered.

Behind them, a voice said, “Took you long enough.”

Dean turned and found Sam standing there, arms crossed, eyebrows raised.

Dean flushed. “How long have you been—?”

“Long enough to stop crushing on Cas and start shipping you two way too hard.”

Dean groaned. “Please never say ‘shipping’ again.”

Sam smirked. “No promises.”

Cas gave a little bow. “Your wingman services were appreciated, Samuel.”

Sam winked. “Anytime, Cas.”

Dean looked between them, incredulous. “Wait. You both knew?”

Cas nodded. “Dean, I knew the second you got angry about Sam offering me his leftover brownies.”

Dean pointed at Sam. “And you—?”

Sam shrugged. “I may have played it up a bit. Just to push you.”

Dean stared. “I hate both of you.”

Sam laughed. Cas just smiled, content.

Dean rolled his eyes and slung an arm around Cas’s shoulders anyway.

“Idiots,” he muttered.

But he was smiling too

Chapter 2

Notes:

Sam’s POV

Chapter Text

Sam had always liked people who didn’t talk just to fill silence.

So when Dean introduced him to Castiel for the first time—a guy with impossibly blue eyes, rumpled clothes, and a voice like he read poetry for fun—Sam was immediately intrigued.

They’d been in the kitchen. Cas had been polite, quiet, and surprisingly kind for someone who looked like he belonged in a moody black-and-white film.

And when Cas had asked him a question about the book he was reading instead of brushing him off like Dean’s other friends?

Yeah. Sam was gone.

At first, the crush was harmless.

Cas liked strange books and stranger metaphors, and he always made Sam feel like his opinions mattered. He’d listen—really listen—and then tilt his head like he was considering everything deeply, even if Sam was just ranting about finals or cafeteria pizza.

And okay, maybe Sam talked about Cas a little too much.

Maybe he asked Dean, “Is Cas coming over?” more than a normal amount.

And maybe he saved a couple of their text conversations just to reread when he couldn’t sleep.

It wasn’t like he thought anything would happen.

Cas was older. Dean’s best friend. Totally not into him.

But still. It felt good to like someone who made the world feel a little less sharp around the edges.

Then came Spring Fling.

Sam hadn’t expected Cas to show up—but when Dean said he was going, Sam saw his chance. He texted Cas with what he told himself was a casual invite.

He still remembered the way Cas had smiled when he saw him at the gym, and the way he looked so out of place under the disco ball light—like someone who’d wandered into the wrong world but was kind enough to stick around.

They’d danced near each other. Not together, not really. But enough for Sam to get flustered when Cas helped fix the pin on his boutonniere and murmured something about “symbolic color choices.”

And every time Sam looked over at Dean that night, Dean looked… tense.

Withdrawn. Moody.

Sam didn’t get it at first. But then he really started watching.

Dean wasn’t annoyed that Cas was there. He was annoyed that Sam was with Cas.

That’s when something clicked.

Sam didn’t stop liking Cas. But his feelings shifted—just a little. He wasn’t dumb. He saw the way Cas’s gaze lingered on Dean. The way Dean softened around him, even when he was being his usual sarcastic self. The way they talked in half-sentences like they didn’t need the rest.

So Sam leaned in.

He started texting Cas more often. He showed up “coincidentally” at that bookstore. He made sure Dean knew just how charming Cas was—talked about Cas’s reading tastes, complimented his tie, asked him to explain obscure metaphors with his hand on Cas’s arm.

Every time, Dean got a little grumpier.

A little more obvious.

And Sam, bless his chaotic little heart, just pushed harder.

Not to steal Cas.

To light a fire under Dean’s jealous, emotionally-stunted ass.

By the time Dean finally stormed off to talk to Cas behind the school, Sam had already decided to sit back and watch the drama unfold. He didn’t expect to walk in on the kiss, but when he did?

Totally worth it.

He folded his arms and grinned. “Took you long enough.”

Dean turned pink. Cas didn’t even look embarrassed. Sam had to fight the urge to give them both slow claps.

And when Cas thanked him for his wingman services?

Sam nearly died of smugness on the spot.

Later That Week…

Sam scribbled in his notebook, legs kicked up on his desk, journal open to a new page.

APRIL 14TH, 3:42 PM

Operation Destiel: SUCCESS.

Dean’s less moody, Cas is still quoting dead poets, and they’re finally holding hands like it’s not the most obvious thing in the world.

I’ve downgraded my crush to a deep admiration and mild fondness. Also: a weird kind of pride. Like I’m a mom watching her idiot sons finally figure it out.

Might start charging for emotional matchmaking.

Step one: make them jealous.
Step two: gently gaslight them into spending more time together.
Step three: let true love do the rest.

I’m a genius.

He smirked, closed the journal, and grabbed his phone.

From: Jess
“Wanna hang out this weekend? There’s a lit club meet at the library.”

Sam grinned.

Maybe it was time to aim his crush energy somewhere it might actually go somewhere.

Notes:

Hope you enjoyed!