Work Header

Hello From the Sin Cave

Work Text:

Tony was coming off a three day bender in his workshop, running on coffee and gasoline. His clothes smelled like burning plastic (an incident with his smoothie cup) and there was oil slicking up his hair.

He stumbled into his kitchen and into his coffee machine.

He pawed at the buttons until it started to pour coffee into the pot, grumbling at it.

A ringing chime sounded from his phone and he slammed his hand down on it, fumbling for the right button.

“Hnng,” he said as he pulled it up to his ear.

“Tony?” Bruce said.


“Oh my God, Tony, have you been in the lab? Is that why you haven’t been answering my phone calls?”


“How long have you been in there?”




“Oh my God! What have you been doing?”

Tony’s eyes burned with the horrors of what he’d seen. “Ssssssssssinning.”

“Tony Stark, you cannot do that! Do you want me to call Pepper?”

“No! Don’t call Pepper, she’ll be mad.”

“She should be, you’re spending all your time in that dank, dirty cave you call a lab. It’s bad for your health.”

“I’m gonna go.”

“I’ll be over later.”


Tony hung up the phone and took the mug, cradling it in his hands.

“I can drink it out of the pot,” he murmured to himself. “People do that. I can do that.”

He took a long drink and burned his mouth.

Looking over the top of the pot, he choked.

A half naked blond man toweling his hair off walked by the window of the apartment across from Tony’s.

“Oh my God,” Tony whispered. He wandered over to the window and stared.

He had a towel slung around his waist, water dripping from his chest.

“Holy shit,” Tony whispered.

This guy was the hottest guy Tony had ever seen. His muscles had to be the work of a god, and his jaw was chiseled as if from stone.

As Tony was staring, mouth open, probably drooling embarrassingly, the guy looked up.

“Shit,” Tony said and ducked.

He landed underneath the window, spilling coffee all over the floor and on himself. “Ouch, fuck, motherfucking ouch.”

He peeked up over the windowsill.

The guy was still there, looking out the window. When he saw Tony he waved.

“Shit,” Tony ducked back down.

What should he do? The hottest guy in the world had just caught him being a peeping Tom. Not on purpose, but still.

He got up, turned around, crouching and looked back up.

The guy looked at him for a moment before waving again, hesitantly.

Tony scrambled back, slipping in the coffee.

He groaned as he hit the wood floor.

When he looked back up, the guy was looking into his window with concern.

Tony had to do something, had to say something. He couldn’t just wave back, he had to use words.

He looked around for paper and a marker.

He found some in a junk drawer and scribbled on it before grabbing tape too.

He slapped the paper against the window and slid some tape across the top.


Tony sat beneath the window again, peeking above the sill.

In that moment, Tony felt very stupid. He was crouched below a window, looking into his neighbor’s apartment, with coffee seeping into his socks and the back of his shirt.

Plus, he’d just taped a sign to his window that said hello from the sin cave. What was he thinking?

The guy stared in horror at Tony’s sign for a minute.

And then he burst out laughing.

He was laughing at Tony’s ridiculous sign.

Probably the best reaction Tony could have asked for, to be honest.

Tony watched as he disappeared for a few minutes, leaving a view into his apartment unobstructed.

Wet and Naked Hottie reappeared quickly, taping up his own sign.


A choked, startled laugh rattled it’s way out of Tony’s throat and he wheezed with the giggles, fingers gripping the windowsill in an effort to stay upright.

The hot guy looked beneath the sign, grinning over at Tony.

They grinned at each other for a moment.

Then the hot guy looked down and seemed to remember that he had the towel wrapped around his waist.

He looked back at Tony and made a series of gestures and pointing to tell him he was going to go get dressed.

Tony nodded and waved goodbye.

The hot guy waved again and disappeared.


“Hello from the sin cave?” Bruce said, leaning out the window and looking up at the sign still hanging.

“Oh yeah,” Tony said, taking a sip of coffee. “I was just saying hi to my neighbor.”

“And you chose to do so referencing your location as the sin cave?”

Tony nodded. “Yep.”

“You do know what that makes it sound like, right?” Bruce said. “It sounds like you have a sex dungeon.”

Tony thought about that. “Oh yeah. I guess it kind of does.”

“That doesn’t bother you?”

“Not really.”

Bruce looked back out the window. “So what are you going to say back?”


“Well,” Bruce looked at the neighbor’s response. “He said something back to you. Don’t you wanna continue the conversation?”

“Oh,” Tony said in mild surprise. “Yeah, I guess I do.”

He meandered over to get more paper.

“What are you going to say?” Bruce asked.

“None of your business,” Tony said pleasantly.

He tore down the other sign and stuck the new one up.

Bruce poked his head out and looked up at it. “But if I step into a church I will burst into flames.” He came back inside. “Tony, you can’t say that to someone who thinks you have a sex dungeon. It’s not good for your image.”

“What image is that?”

“I don’t know. Whatever image you’re giving off.”

“Whatever. I guess we’ll know what he thinks later, won’t we?”

“I guess we will.”

They spent the rest of the day eating chinese food in front of the the tv, occasionally dozing off.

They woke up after a while, moving about the apartment.

“Hey Tony,” Bruce said. “You’ve got a reply.”

“What?” Tony slipped in his socks scrambling to the window.

Taped up in the neighbor’s window, the paper said  “Should I come over and exorcise you?”

Tony laughed. “Oh my God. This is great, this is amazing.”

“Listen,” Bruce said. “I’ve gotta go but you let me know how this works out.”

“Sure thing,” Tony said, pulling out more paper.

Bruce left and Tony scribbled his reply on the paper.

He taped it to the window and stepped back, examining it. Nodding in approval, he left it to it’s own devices and went back to his lab.

Later that afternoon, he got a call from Pepper.

“Why do you have a sign in your window that says “You can do whatever you want to me?””

“Are you outside my apartment?”


“Then why haven’t you come in?”

“Because I was distracted by the sign in your window that was explicitly coming on to the street.”

“I wasn’t coming on to the street, I was coming on to my neighbor.”

There was a pause on the line. “Tell me it was after a few interactions and this was not the first thing you said.”

“We’ve been communicating through window signs.”

“How romantic.”

“Is there a reply?”

“Dear god, there is.”

“What does it say?” Tony jumped up and ran for the door to look.

“It says “Do we have to do it in the sin cave,”” Pepper said. “Tony.”

Tony giggled as he looked at the sign across the street. “Yeah?”

“What is the sin cave?”

Tony paused. “...My lab.”

“That’s not what it sounds like,” Pepper said. “It sounds like a sex dungeon.”

“I know,” Tony said. “Bruce already said that.”

“I’m coming up.”

Tony was still looking at the sign when Pepper arrived, giggling to himself.

“Tony,” she said.


“Why are you doing that?”

“Doing what?”

“Being creepy.”

“I’m not being creepy,” Tony said indignantly. “I’m laughing.”

“You’re chuckling.”

“That is the same thing,” Tony got the paper out again. “Help me decide what to say.”

“How about “Communicating via window notes is weird and we should have an adult conversation?””

Tony nodded as he wrote his new note. “I like it, but I have a few changes.”

He slapped it up against the window.

Pepper lifted it up to read it. “Do you want me to go to church or not? Tony.”


“What does that even mean?”

“He told me to go to church, but I can’t unless he exorcises me.”

“In the sin cave?”

“In the sin cave.”

She stared at him.

He looked back at her, unblinking.

She sighed and dropped her shoulders. “Have you eaten?”

“What time is it?”

“About seven.”

“I ate earlier with Bruce.”

“Let’s go get dinner.”


Steve pulled his phone out of his pocket and brought it to his ear. “Hello?”

“Why do you have a sign in your window that says “Do we have to do it in the sin cave?”” Bucky’s gruff voice said in his ear.

“Are you by my apartment?” Steve asked.

“No, I’m in your apartment.”

“Why are you in my apartment?” Steve asked. “I’m not there.”

“Yeah, I gathered that, thanks Stevie.” Bucky said and Steve could picture him rolling his eyes. “Besides, you don’t get upset when Natasha’s in your apartment when you’re not home.”

“Natasha goes to my apartment when I’m not home?”


Steve sighed. “There’s a cute guy that lives across from me and we’ve been putting up signs to talk to each other today.”

“The one who has a sign in his window that says “Do you want me to go to church or not?”

Steve laughed. “He replied?”

“I guess so.”

“Alright,” Steve said. “Don’t reply, okay? I’ll be home in a little bit.”

“Good, maybe you can stop Barton from cleaning out your fridge.”

“Clint’s there too?”



The signs continued for a few weeks, ranging from cute to sexual to funny. They formed their own inside jokes.

Steve and Tony both got several calls from their friends throughout the weeks, wondering why they had signs in their windows.

It was often the best part of their day, something they looked forward to, ran home to see what their reply was.

A few weeks in, Tony was taping up his latest response (A sentient toaster is not an evil toaster) when he saw a movement in the apartment.

He ducked and watched over the windowsill.

As he watched, a red headed woman with a towel around her and dripping hair walked by.

Tony’s stomach dropped.

Of course Hot Guy had a girlfriend. Clearly whatever he and Tony had been doing had been a joke, a way to kill time.

Tony sat back and crossed his legs, staring at the wall. Should he play it cool? Should he mention it?

He looked around and his gaze caught on another sheet of paper. He pulled it to him and stared at the white blankness.

Finally, he slowly dragged the marker up and down, writing his message.

He taped it carefully up under the other one.

By the way, your girlfriend is pretty

He stared at it for awhile, deciding whether or not to tear it down.

He decided to leave it up, walking away to spend as many hours as he could in the lab, forgetting about the pretty girl in the towel.


Steve let himself into his apartment, bag of groceries in his arms.

He jumped when he saw Natasha sitting in her sweats on his couch.

“What are you doing here?”

She shrugged. “I wanted a shower after my workout and your place is closer to my gym.”

“Why don’t you shower at the gym?”

“Because you buy the nice smelling bodywash.”

Steve rolled his eyes and began unpacking his groceries.

“By the way you have a message from your hottie across the street.”

“Yeah?” Steve left his groceries and rushed to the window excitedly.

“What’s it say?” Natasha said, turning the page of her book.

Steve laughed. “It says “A sentient toaster is not an evil toaster.”” Then he looked below. “Wait...”

“What?” Natasha looked up.

“There’s another note,” Steve said, casting around for his paper and pen that he had begun to keep by the window.

“What’s that one say?”

“It says my girlfriend is pretty.” Steve said, taping up his notes, two also.

Natasha stood and came to look at the neighbor’s notes. “Huh. You think he saw that picture of Peggy?”

Steve looked back on his wall, decorated with pictures. A big one of him and Peggy was centered. “I don’t think you can see that all the way over there.”

Natasha shrugged. “Maybe you can.”

Steve looked back and forth. “Maybe.”

“Hey, I think Clint is bringing over chinese food.”

“You guys know this is my apartment, right?”


“So this thing is still going, huh?” Bruce asked, looking out the window.

“Yeah,” Tony said. “But I’m not sure it’s going to last.”

“Why’s that?”

“He’s got a girlfriend.”

“Are you sure?”

“A girl in a towel walked by the window.”

“But he says he doesn’t have a girlfriend.”

“What?” Tony’s head snapped up and he raced to the window to slide in next to Bruce.

Two signs were taped up; one said “A toaster that sets itself on fire is an evil toaster” and one below that said “I haven’t got a girlfriend.”

Tony stared at it for a moment. “He hasn’t got a girlfriend.”

“That’s what it says.”

Tony whooped and grabbed his paper.

“Maybe you could ask him out, instead of taping notes to your window.” Bruce suggested.

“Bruce, you have no sense of romanticism,” Tony said, taping his new notes to the window. “I’m wooing him.”

“You’re hitting on him via marker.”

“Which is my way of wooing.”

“Then you’re screwed.”


“New note,” Clint said mouth full of food, stopping at the window.

Steve hopped the couch and went to look.

“What’s it say?” Sam asked.

Steve grinned. “It says “The toaster only sets bagels on fire.”

“Oh good,” Bucky said. “I was worried that you were having a normal conversation for once.”

“Did he say anything about you having a girlfriend?” Natasha asked.

“Yeah,” Steve said. “His other note says “What about the gorgeous redhead?””

“He spotted our fair lady Natasha,” Thor said.

“Must have,” Steve said. “Don’t know why he thought you were my girlfriend though.”

“I was walking around in a towel.”

Clint frowned at her. “Why were you walking around Steve’s apartment in a towel?”

She kissed his cheek. “Because I’m secretly sleeping with him on the side.”

“Yeah, you wish,” Clint scoffed, then frowned down at his shoes. “Wait.”

“What is your response?” Thor asked.

“I’m saying “Bagels are a huge percentage of what goes in toasters.””

Bucky rolled his eyes. “About Natasha, dummy.”

“I’m saying that she’s a friend.”

“You ever think about asking him out?” Sam asked. “You know, instead of communicating through your window?”

“We’re still...” Steve turned pink. “Flirting.”

They all “ooohed” and Steve turned even pinker, saying, “Shut up.”

“Flirting, huh Stevie?” Bucky said. “I was not aware you possessed such a skill.”

“I said shut up,” Steve said.


“He just put up another note,” Bruce said.

Tony looked out. “Natasha’s just a friend.” A slow grin spread across his face. “Just a friend. This is awesome. This-” He grabbed his paper. “Is awesome.”


Steve watched as his neighbor wrote a new note and put it up.

“What’s it say?” Bucky asked.

Natasha stood by Steve and read aloud. “You sure?”

The neighbor spotted Natasha and pointed.

Steve pointed at her too, raising his eyebrows.

Neighbor nodded.

Steve put his hand over Natasha’s face and turned it, wrinkling his nose and sticking out his tongue. “Blech.”

“Thanks,” Natasha said, muffled by his hand.

The neighbor grinned widely at them. Then, a curly haired guy appeared next to him.

Steve raised his eyebrows and pointed at Neighbor’s friend.

Neighbor got a new sheet of paper and put up another message. “Bruce is also just a friend.”

Then he made a gagging gesture while pointing at the guy, who was now making a pained expression.

Steve laughed and waved at Bruce.

Bruce waved back, before ambling away.

Neighbor waved too, gesturing to let Steve know he was going to follow Bruce.

Steve waved goodbye and turned back to his friends, a doofy grin on his face.

Bucky grinned at him. “Look at you, you loon, you’re smiling like an idiot.”

“Shut up,” Steve said, but he was grinning.


“You have got to stop this,” Pepper said.

“Stop what?” Tony asked.

“Talking to your crush with marker and paper.”

Tony sighed. “I told you. I’m wooing him.”

“Don’t you think you’ve wooed enough?”

“Not yet,” Tony said. “I need to be sure he likes me.”

“You need to be sure?” Pepper cried. “Tony, the man has spent four weeks talking to you exclusively through notes, making sure to leave a response whenever he can,and they’re almost always flirty!”

“What if he’s not that invested? It’s not that hard to write a note and tape it up, Pep.”

“Bruce said he told you he doesn’t have a girlfriend.”


“So,” Pepper said. “that’s clearly an invitation. He’s letting you know he’s unattached.”

“What’s your point?”

“He wants to be attached.” Pepper said. “To you.”

Tony tapped his marker against his paper. “I’ll think about it.”


Tony was heading out, keys in hand and whistling, when he saw his hot neighbor about to enter his own building. He stopped in his tracks, mouth still forming a pucker to whistle.

His neighbor looked up and caught his eye. A slow grin spread across his face as he looked at Tony, eyes lighting up.

He slowly walked towards Tony, as if he was careful to walk to quickly and scare him.

Tony moved forward too, once he remembered how to work his feet.

“Hey,” he said when they reached each other.

“Hi,” his hot neighbor said, still grinning.

“Um,” Tony said. He stuck his hand out. “My name’s Tony. I don’t think I ever said that.”

“I’m Steve,” his hot neighbor-Steve- said, taking his hand. “Probably didn’t say that either.”

They grinned at each other.

Steve chuckled. “This is kind of surreal.”

“Yeah?” Tony said.

“Yeah,” Steve said. “I mean- I feel like I know you so well, but I just learned your name.”

“Oh yeah,” Tony laughed. “That is weird.”

“So um,” Steve’s eyes flickered between Tony’s face and his apartment. “Can I invite you up for a cup of coffee?”

Tony grinned. “I’d like that.”


Three years later, the window notes were still going. Requests for dates, reminders for important events, jokes they’d heard, sweet sayings.

Marriage proposals.

Steve almost dropped his groceries when he saw the sign in the window that said “Marry me?”

He ran to the window, convinced he was seeing things. When he was certain he wasn’t hallucinating, he gasped.

“Oh my God,” he grabbed his paper and scribbled on it before running back out the door, abandoning his groceries and leaving his door wide open.

He ran across the street and buzzed up to Tony’s apartment.

Beneath the window was Tony, on one knee, holding a ring.

“Hi,” he said, smiling nervously.

“Hi,” Steve breathed.

He walked over to Tony, heart beating wildly.

“Steve,” Tony said. “Will you marry me?”

Steve reached into his jacket pocket and pulled out his paper, unfolding it.


Tony grinned up at him and stood, kissing him square on the mouth.

“Oh my God,” he whispered as they pulled apart. “We’re engaged.”

“We’re engaged,” Steve said back, kissing him lightly.

“Oh,” Tony said. “Here’s your ring.”

He slipped the ring on Steve’s finger and kissed him again.

Steve pulled him close, feeling like his heart might burst with happiness.

“Our friends are gonna be so pissed I proposed with a note,” Tony said.

Steve grinned into the kiss. “It was perfect.”