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Title: Argumentative Threesome – Stetopher Week 2025

TW Disclaimer: All rights reserved to Jeff Davis and MTV. This fanfiction on the other hand is entirely mine. No money is made with this, though reviews are more than welcomed.

Tags: m/m/m, polyamory, diner AU, fluff, arguing as a love language

Main Pairing: Chris/Peter/Stiles

Teen Wolf Characters: Mieczysław 'Stiles' Stilinski, Chris Argent, Peter Hale, Erica Reyes

Stetopher Week Day 1 Prompts: two plus one | v turned o

Summary: Chris and Peter walk into a diner in the middle of an argument and, to both their surprise, the cute barista decides to just join their argument. Peter is happy to finally have someone eager to argue with him and Chris is happy someone else is arguing with his husband.

Argumentative Threesome

Stetopher Week 2025

The first time it happened, Chris and Peter had just gotten out of the movie they’d chosen as this week’s date. Since both Chris and Peter were workaholics, they had agreed early on in their marriage that one night a week was fixed date nights, no work, no other responsibilities, only them. They alternated who organized it and what they did, but Friday night was theirs. This week had been Peter’s pick and somehow that had ended them in a pretentious murder mystery movie. Quite frankly, Chris had been over it the moment they left the theater. However, that wasn’t how Peter rolled.

No, Peter loved to argue. It was the way he engaged with pretty much everything. Books, movies, shows. He wanted to debate what was well-written, what was poorly executed, what he liked, disliked, thought worked or didn’t work. Chris supposed that argumentative nature was part of what made Peter such a brilliant lawyer. The only problem was that this wasn’t how Chris liked to engage with media. To him, watching a movie was mindless entertainment where he could finally turn his brain off and not think, finally relax after an exhausting day at work. When the movie was done, it was done, and he was ready to move on with his day. He didn’t dwell on these things.

It was one of these things that were just a part of marriage, to Chris. He didn’t think couples should be a hundred percent the same. Differences were what made people complimentary. And marriage meant to make certain compromises. This was a minor thing, Chris didn’t care about it, but he knew that Peter cared about it a lot, so Chris indulged his husband and argued with him about whatever piqued Peter’s interest about the movie or show they were watching. He knew it wasn’t exactly what Peter wanted – which was what made it a mutual compromise – because Peter would like to be met in wit, but Chris was more of a soundboard for Peter to bounce his own arguments off. Chris couldn’t, didn’t want to, get deeply into these things that he didn’t care about, but he gave some argument, enough to keep Peter going. It was a compromise and it worked. Until that day.

That day, after Chris and Peter had gotten out of their date night movie, they decided to go to a little diner around the corner because they hadn’t gotten dinner yet. They were still in the middle of their argument when they went to the counter to order their food and sit own at the bar.

“I am just saying that the protagonist was painfully plain,” Peter complained. “All he had going for himself were his high morals and goody two shoes attitude. That is why we should root for him?”

“Yes, Peter,” Chris heaved a sigh as he sat down. “We’re supposed to root for the good guys.”

“It’s just hard to do that when the ‘bad guys’ get all the nuance and interesting bits.”

Both Chris and Peter paused at that and turned toward the guy behind the bar. He was young, their daughters Malia and Allison’s age, bright-eyed and very, very pretty. He’d also just inserted himself into their conversation unprompted. Chris winced, assuming this was his subtle way of telling them that they were in the diner now and should maybe pay attention to him and order their food. Peter did apparently not have the same inclination, because he leaned in with sparkling eyes.

“Exactly!” Peter agreed enthusiastically. “The so-called bad guy was motivated by the loss that shaped him as a person, driven by his need for revenge. The good guy is just… good and does what is seen as morally right. That’s not a motivation, that’s boring.”

“But you see, murder is bad,” the cute boy said with a straight face. “Therefor, the character who kills is bad. And that’s where it ends. Media literacy is decaying and it’s sad.”

“You have no idea,” Peter heaved a sigh.

“I am literally in college with a minor in media culture studies,” the cute boy said dryly. “The amount of people who take classes in this degree because they think they can watch movies mindlessly and apply their non-existent critical thinking to it is staggering.”

“My condolences,” Peter said genuinely.

“Stiles, stop flirting and take their orders,” a blonde girl yelled from the other end of the bar.

The boy – Stiles – blushed brightly and glared at her. “Shut up, Erica, I am not flirting and he is clearly here with his hot date anyway! I just can’t resist a good argument.”

Chris pursed his lips, oddly charmed by that. There was a directness about the boy that appealed to Chris. He turned to look at the menu to pick something to eat, tuning out the way Stiles and Peter continued talking about the movie, until Chris had made a choice.

“-I am just saying that there was a clear disconnect in how much focus the movie put on the importance of that family when it was just fully unrelated to the main character,” Stiles argued. “And there would have been more payoff for this if they had done a reveal that he was actually the villain’s son. Especially since they did do the ‘child he never knew about’ plotline in the sequel book, like, instead of just a random new character, that baby could have been our titular lead!”

“Only that it’s an overdone plot,” Peter countered unimpressed.

“Overdone?” Stiles’ voice pitched a little. “It’s not overdone, it’s a timeless classic! Star Wars may have made it huge, but that doesn’t mean nobody can do it. That’s how tropes and themes are born and these things are wildly important in fiction.”

Peter tilted his head and nodded slowly, eyes intense as he regarded Stiles. “Point taken. Perhaps I just don’t like him enough to have him be the lost child.”

Chris took the pause in argument to clear his throat. “I’ll take a caramel shake and a bacon burger.”

Both Stiles and Peter looked startled at that, like they had forgotten that they were in a diner and that Stiles was working here. Chris snorted softly at that, before the boy scrambled to get back to work. Peter shot a glance at the menu before placing an order of his own.

/break\

The second time it happened had been intentional and instigated by Chris. Because they had already gone five rounds themselves and Chris had tired himself out on the argument. It made him remember the little diner and the little spitfire behind the counter who had so eagerly argued with Peter. So when it was Chris’ turn to plan their date that day, he took Peter to Claudia’s.

“A diner,” Peter raised an unimpressed eyebrow. “I mean, the food was excellent last time, but it’s not exactly date night dinner levels, Christopher.”

“I want a burger,” Chris shrugged as he pushed into the diner. “And you want an argument.”

Peter blinked at him in curious surprise but he followed his husband anyway. To Chris’ relief, Stiles was behind the counter once again. He was in the middle of an argument with the blonde from last time, Erica, as the name-tag read. Chris smiled amused as they approached the counter.

“Hello,” Chris said, interrupting the two, who froze like bunnies. “I’d like a bacon burger and a beer and I’d like to know if you read the latest book in the Moonlight Mysteries series.”

“The Erlking’s Echos in the Evening?” Stiles blinked at him. “Yeah, I finished it three days ago?”

“Wonderful,” Chris heaved a relieved sigh and pushed Peter into a seat. “Peter would like to argue about the parallel drawn between Julian and Dylan in their stay at the Alder Asylum. I’ll be over there, at that table, enjoying my burger, and picking him up again when I’m done.”

For a long moment, all three – Peter, Stiles and Erica – stared at him in bafflement, before he turned his back and went to sit down. Genuinely, he could not listen to another word about this damn book. Yes, he’d read it, yes, he’d moderately enjoyed it. He found it weaker than the rest of the books, because this was a murder mystery series and the murder mystery was quite the sideline in this one, as it focused on the visceral experience of one of its two leads being stuck in an asylum against his will. Which had already happened to the other lead two books prior and Chris thought it was boring.

Peter, on the other hand, was absolutely obsessed with it. The injustice of Julian’s incarceration after he had been arrested by Dylan’s former partner Joey for crimes he never even committed. Crimes he had planned, when fully out of his mind, before they were stolen and executed by someone else. The parallel between Julian’s forced stay in Alder Asylum, after Dylan had been in it. Peter loved anything that paralleled Julian and Dylan, because he thought that was what made them so compatible. Which was the point where he really lost Chris, because Chris was not interested in speculating about potential future relationships or anything.

Dylan and Julian had an interesting dynamic right now, the cop and the private investigator who solved supernatural crimes together, Julian a werewolf and Dylan a human not in the know but constantly touched by the supernatural. It was fun, for Chris, the escapism of reading about werewolves and crime that didn’t affect him. But Peter? Peter wanted to analyze, to dissect, take every aspect apart. That was just tiresome for Chris and he had thought – hoped, really – that Stiles might be up for the challenge. Considering the first argument Chris and Peter had walked into Claudia’s with had been about the adaptation of the first book in the Moonlight Mysteries series, he had had high hopes that Stiles was also reading the books and could take this argument from him.

Two hours, one burger, one big Sundae and three beers later, Chris saw that he had been right on target, because Peter and Stiles, whose shift had ended a bit over an hour ago, were still in the middle of a heated debate about the significance of the villain of this book being the same orderly who had abused and mistreated Dylan during his own stay at the facility.

“And I’m just kind of in love with the double-meaning word-play of the name, you know?” Stiles offered, waving around the straw from his milkshake a little. “Taking the name-giving Alder, translated to German as Erle and leaning into the Erlking poem for the villain. At least they made him German to make that bit make sense.”

Chris smiled pleased as he watched his husband’s reaction to the boy’s words. This had been his best idea in a long time, outsourcing his arguments with his husband to someone else.

/break\

Chris turned off the TV, bracing himself for what would follow. Their arguments after a regular episode of TV were perfectly fine, usually Chris even enjoyed them. Because an episode was forty-five minutes long, it didn’t give Peter enough fodder to go on for three days like a movie might. It wasn’t that Chris hated discussing fiction with his husband, after all. He just tired when it got too heated or intense or went on for too long, because he wasn’t that invested. So regular after TV discussions were perfectly fine. Season finales however, especially depending on their execution, could drag on for a while. Peter liked to reevaluate the entire season under the new light brought to it by the conclusion. When Chris turned to look at his husband, there was that eagerness.

“Would you like a burger, love?” Peter asked, startling and confusing Chris. “I feel peckish, I think I would enjoy a good club sandwich right about now. Claudia’s had a great club sandwich.”

Chris snorted, his own eyes sparkling fondly as he regarded his husband. “Sure, let’s go to the diner and hope Stiles also watches that show, mh.”

“Oh, I know he watches it. He brought it up in our discussion of The Erlking’s Echos in the Evening,” Peter made a dismissive hand-motion. “And knowing him, he certainly already finished.”

“Knowing him?” Chris raised both his eyebrows at that. “You talked to him twice.”

“For a total of over three hours,” Peter countered dismissively. “Besides, you can tell so much about a person when you get that deep into what they like and dislike.”

Chris smiled to himself while the two of them got their jackets on and headed to the diner.

/break\

The fourth time they went to Claudia’s so Peter could argue with Stiles, they weren’t as lucky as the last three times. The diner was actually packed and beyond quick greetings, Stiles and Peter only managed about three sentences about the movie at hand. When Stiles came to bring them their check and get their money – with the same ridiculously high tip they’d left the past three times – Stiles held out his hand in a demanding manner afterward.

“Gimme your phone,” Stiles ordered. “So I can give you my number. I still got three hours on my shift. Call me in four hours so we can actually get into this. I have opinions.”

Peter perked up delighted at that and was quick to hand over his phone. Chris didn’t really know if this was a good idea or not though. Coming here, into the diner, for Peter and Stiles to argue was one thing. There was a clear boundary set here. It happened only in this setting. Exchanging numbers? They could reach out to each other at any time, there was no illusion of boundary at all. It wasn’t necessarily that Chris was worried Peter would cheat on him with Stiles. He knew his wolf was deeply loyal in nature. Still, he was concerned on how the lines could blur from hereon out.

/break\

The fifth time Chris went to the diner, he went there alone, actually. Peter was away on a case, with a rich client who had gotten into trouble in Las Vegas, and the house felt a little too big and a little too empty to be in it alone all day, so Chris had decided to move his game to the diner.

He liked to play chess, against himself. Peter indulged him in it occasionally, but the man’s heart wasn’t wholly in it. Yes, Peter was a clever strategist, but he didn’t quite enjoy chess. Not the way Chris did, anyway. And that was fine, the casual games they shared were nice and otherwise, Chris liked to play against himself. Which he figured he could do at Claudia’s just as well as at home.

So he went to what he was slowly starting to consider his booth, ordered his burger and a coffee and then set the game up for himself. He played at a casual, slow pace, no partner to play against who put him under time pressure (Peter could be horribly impatient at times). After he finished his meal, he headed to the toilet and when he came back, he could have sworn someone moved his pieces.

“Oh, yeah, Stiles messed with your board earlier,” Erica pointed out when Chris kept staring at the board in bafflement by the time she came to refill his coffee. “Don’t mind him, he just can’t resist these things. It’s a Stiles-thing, just set the toys back.”

“They’re not toys,” Chris shot her a glare.

Erica’s eyes lit up. “I know. I like messing with Stiles that way. There’s a horsey and there is a big tall tower, toy figures. I’ll tell him to leave it alone, but it will absolutely be futile.”

“No, it’s… it’s fine,” Chris turned back to the board and rubbed his face slowly. “He just… put me in check. When I thought that color was actually about to win the game.”

Erica blinked with a slightly blank look on her face and nodded before she walked away, apparently no longer caring. Chris all the while focused on the chess game that just got much more interesting. He made his own move and then he went outside to call Peter, as they had agreed to. When he returned, he was in check-mate. He stared at the board for a long moment, making sure that Stiles hadn’t cheated just to truly mess with him. But no, he had moved according to the rules. He had just… outsmarted Chris. Looking up, he tried to find the boy.

“Where is Stiles?” Chris asked when he approached Erica at the counter.

“He’s in the back, sorting through deliveries with Isaac. They’re gonna be a while, it’s a lot of stuff,” Erica paused. “Want me to get him?”

No. That was ridiculous. Sighing, Chris shook his head and instead picked up his board and game.

/break\

Chris kept his eyes on Stiles the entire time he was at the diner the next time he went. Watching and waiting for the boy’s break. The moment Stiles high-fived Isaac in passing and declared himself on his break, Chris caught the boy’s wrist and pulled him closer, startling him. Those pretty doe-eyes stared at him largely and then Chris motioned at the set-up chess-board.

“Tell me off if this isn’t how you want to spend your break, but-”

Chris didn’t even get to finish his sentence. Stiles was already plopping down opposite him and reaching across the table for Chris’ plate to steal a handful of fries. Frighteningly enough, Stiles stuffed them all in his mouth at once. Chris tried not to focus on where his brain went at the way Stiles’ cheeks bulged and how his pink lips wrapped around his fingers to lick off grease and salt.

“You know, if you become a regular, I will enforce that you order a salad at least every third time,” Stiles declared while making his move. “Because this is your fifth bacon burger.”

“The burgers here are great,” Chris shrugged, considering his own move. “Besides, I don’t think you get to tell the customers what they can and can’t order.”

“I can,” Stiles looked up with raised eyebrows. “It’s my diner.”

For a long moment, Chris stared at Stiles. “It’s called Claudia’s, somehow I didn’t expect that…”

“That’s my mom’s name,” Stiles shrugged. “All the foreign sounding things on the menu are her recipes. I opened the diner to honor her. Everything Polish on the menu, I cook. All the baked goods are Boyd’s and everything else, we kinda both do.”

“You’re… young for a business owner,” Chris said, trying to sound appreciative and impressed.

“Thanks,” Stiles grinned as though Chris had succeeded.

Chris smiled briefly at the boy before making his own move and then reaching for the fries.

/break\

Chris was in his office, going through the latest orders for his shop. He ran a camping and hunting store, it was how he had reimagined himself after turning his back on his father and his family’s type of hunting. Soft knocking caused him to look up and then his husband stuck his head into the office, his phone stuck between his ear and shoulder.

“Dear, I’m on the phone with Stiles,” Peter started and Chris smiled amused. “He has Saturday off and was wondering if you’d like to come by the diner for breakfast and a chess-game?”

Before he even had a chance to think about it, he was already nodding. “Yeah, sure. I’d like that.”

Peter smiled pleased at him, nodding and heading back out. “Christopher says he’ll come.”

Only after Peter had left did Chris really think about it. He blinked and leaned back in his chair. He’d been by the diner a couple of times on his own by now to play chess with Stiles. Always on his own time-table, so it only seemed fair that Stiles set a time and date for a change. It was probably inappropriate how often Peter and Chris came to bother Stiles at work, wasn’t it?

It was probably inappropriate how much time Peter and Chris spent with Stiles in general. It had started out innocent enough, with Peter and Stiles’ media debates. But at some point, they’d started blurring the lines, hadn’t they? Was it when Peter started going to the diner alone for these debates? Or when Stiles and Peter exchanged phone numbers and spent hours on the phone with each other? Or when Chris started coming to the diner on his own to play chess with Stiles…?

The office door opened again and Peter entered, no longer on the phone but with a pleased look on his face. “As Stiles and I have come to a stalemate in our argument, we have agreed to rewatch the movie again, together, and make notes to compare afterward.”

They had definitely crossed a line somewhere. Chris furrowed his brows and rubbed his beard. Peter noticed, of course he did, he knew his husband well. Tilting his head, Peter walked over to Chris and perched himself on the edge of Chris’ desk.

“What’s on your mind, darling?” Peter asked, arms crossed.

“You do see it, don’t you?” Chris asked in return, looking at his husband. “Just how much time you and I spent with Stiles, together and separately. What a big part of… us… he is becoming?”

“Adults are allowed to make friends too, Christopher.”

“Is he?” Chris asked, his eyebrows raised as he looked at Peter. “Is that really what he is? A friend? Because we are very explicitly making him a part of our relationship. You go to him to do the things where you and I don’t fully click, I go to him to do the things where you and I don’t fully click. It’s… This is more than just friendship things, Peter.”

Peter’s silence spoke volumes. He pursed his lips and turned his head to look out the window. Chris couldn’t help the twist of his lips, not fully a smile but something akin to it. They were in trouble, weren’t they? It wasn’t helpful that Stiles was breathtakingly beautiful, sarcastic and headstrong. Stiles didn’t just click with them on these things, he also appealed to them both.

“It’s unfair to him, isn’t it?” Peter wondered softly. “We’re using him to get something out of it that we aren’t getting from each other.”

“Exactly,” Chris heaved a sigh.

Both of them remained quiet after that because the clear conclusion was that they should cut back on the time they spent with Stiles. Stiles didn’t deserve to be used like that, as a replacement boyfriend for the things their respective husband couldn’t provide. The problem was that neither of them wanted to distance themselves from Stiles, because that was how important he had become.

/break\

Neither Peter or Chris knew what exactly to do about the boy or their slowly growing feelings for him. They wanted to distance themselves from Stiles some, wanted to set some boundaries. Stiles could be their friend, but that meant they had to separate him more from their relationship.

That didn’t work. At all. If anything, over the following weeks, Peter and Chris were drawn even more into Stiles’ orbit, because their dynamic shifted again when it was no longer just Peter and Chris seeking out Stiles, but instead also Stiles coming to them. He would put plates of dishes in front of them at the diner with food that wasn’t on the menu, letting them taste-test new things he was trying. Relying on their judgment, bouncing ideas off of them.

“You speak fluent French, right Chris?” Stiles asked with a heavy sigh as he slipped into the seat opposite Peter and Chris in the booth. “Think you can help me with something?”

Chris slowly licked his dessert spoon and put it down. “I do. How do you know…?”

“The other week, when you came into the diner, you were on the phone with your daughter and you were constantly switching between English and French,” Stiles replied. “That’s kind of a bilingual thing. I do it with my family too, half a sentence is Polish, the other English.”

“Oh,” Chris blinked, not even remembering that. “Yeah, Allison is studying in Paris and while she’s leaning more toward French because of that, we’re still… What can I help you with?”

“I got an assignment but there are nearly no English sources. I found a lot of French ones though,” Stiles wiggled his nose cutely. “But my school French is, well, school French.”

“Why don’t you get all the books you need and come to our house?” Peter offered with a smile. “Are you free this weekend? Christopher would love to help you.”

Chris shot his husband a pointed look. Yes, he would love to help Stiles, but also, inviting Stiles into their house was the opposite of keeping things separate or setting boundaries. But then he saw the relieved smile on Stiles’ face and the way his eyes sparkled and all he could do was nod.

/break\

Stiles’ diner was more than just a diner and his employees were more than just employees. They were the boy’s betas. The realization came suddenly and surprising, when Chris and Peter took their pack and family to the diner for breakfast, when Allison was in the states to visit for the break. Derek, Laura and Cora all tensed in the presence of other wolves. Yes, Peter had known that Boyd, Erica and Isaac were werewolves. It wasn’t rare, New York was a large city with many packs. However, that many wolves in one diner caused some tensions, leading to growls and to Stiles stepping in – and that was how they learned that Stiles was a human Alpha to his own pack.

It complicated things further, because now they knew their boy knew about werewolves and the supernatural. Plus, there was a certain additional appeal for Peter. Human Alphas were rare and seeing Stiles with his own betas appealed to Peter’s inner Alpha.

On top of that, Stiles now spent time in their territory too. It had felt different, when it was them visiting the diner, a bit more distant. There was nothing distant about Stiles sprawled out on the couch on their patio, a chess-board between him and Chris, while his body was turned toward Peter to continue their argument about… Chris was fairly sure they were actually arguing about one of Peter’s cases this time, but he was also focused on the chess-game so he didn’t pay a lot of attention to the argument happening whenever it was Chris’ move.

“It was just so obviously the husband,” Stiles sighed, shoving Peter lightly. “You have to go back and investigate the crime-scene again, find proper evidence. Clear your client.”

“I’m not exactly an investigator,” Peter drawled dryly before smirking. “You could come with me.”

“You’re not taking Stiles to a crime-scene, Peter,” Chris looked up from the game to glare.

Stiles offered a crooked grin at that. “Aw, it’s cute that you’re being worried, but this wouldn’t be my first crime-scene. Or the first murder I solve. Sheriff’s son, remember.”

“Last time I check, sheriff’s son doesn’t translate to ‘going to crime-scenes and solving murders, darling,” Peter countered, his eyebrows raised.

“It does if you’re me,” Stiles shrugged cheekily, eyes sparkling.

Chris was overcome with the urge to kiss Stiles. He moved the piece in his hand and then got up. Maybe they were going about this the wrong way. Maybe boundaries weren’t working because Stiles was part of their relationship. Because Stiles fit with them, belonged with them. He walked around the table and sat down on Stiles’ other side so he could grab Stiles by the neck and slowly pull him into a kiss. He paused just before their lips touched and searched Stiles’ eyes, but he was only met by eagerness. The kiss was soft and sweet and as soon as he let go of the boy, Peter was quick to steal a kiss of his own. Stiles looked good with red cheeks and kiss-swollen lips.

Stiles grinned mischievously at them. “I was wondering how long it’d take you guys to do that.”

Chris huffed softly. He couldn’t believe that cheeky boy had successfully argued himself into the middle of their marriage, to the point that neither Chris nor Peter could imagine it without him.

~*~ The End ~*~