It started as a joke. Uncharacteristically, the joke was on Tony. Who knew Steve actually had a sense of humor?

First Rule of Engagement: Make sure you have a credible witness (or two).

Tony was bleary-eyed and caffeine-deficient when he left his lab and stumbled into the kitchen in the Avengers' tower. Although he wasn't much of a breakfast person, he did appreciate the smell of bacon permeating the kitchen when he arrived; it smelled almost as good as the freshly brewed coffee. Almost.

Steve was busy at the stove doing his post-morning-workout-for-insane-people thing; cooking more food than any one person should be able to put away in one sitting. Chances were good he was also feeding Natasha who was seated on a stool near the island and Clint who was lurking, but still, that was a helluva lot of eggs.

It wasn't until after he had communed with the coffee gods and imbibed the all important first cup that Tony acknowledged the others who had gathered to eat their morning meal. Understanding that Tony was finally ready to interact with humans, Steve nodded to a plate of toast with a knowing smirk indicating that it was Tony's for the taking.

Tony sidled up to the island where the others were gathered, but he didn't put his coffee down. Clint perched on a stool next to Natasha. A full plate was situated between them; Natasha speared the eggs with her fork while Clint munched on the bacon. Steve was still in serving mode and hadn't settled at the island. Tony watched as he gathered up a bottle of juice to set in the middle of all the plates. When Steve put down the bottle of juice he also slid a small, flat box wrapped with gold paper and a red ribbon next to Tony's toast.

Steve tapped the box and raised his eyes to meet Tony's. "That's for you. A little thank-you"

Tony raised an eyebrow in response. He was surprised, but didn't want to show it. "A gift? For me?" He picked up the box and gave it a little shake. "But what do you give to the man who has everything?"

That smirk was back on Steve's face. There was a look in his eyes too; he was a little too pleased with himself. Tony's eyes flicked to the other two seated Avengers. Barton was still more interested in bacon than the box, but Natasha looked intrigued - or as intrigued as she would allow herself to appear. They didn't seem to be in on Steve's surprise.

Tony put down his coffee mug and impatiently pulled the tail of the red ribbon. The bow slid apart easily into his hand. The gold paper was swiftly ripped and tossed aside. Tony gave the box a sharp shake and the bottom disengaged from the top. When Tony pulled aside the red tissue paper, the gift was revealed. Nestled in the confines of the slim box was a pair of tan, brown and navy argyle socks with maroon piping.

"Socks?" Tony was incredulous and a little confused.

"Grandpa socks," Steve corrected. Clint huffed a laugh that made him choke on his bacon. Natasha's lips curled up in a half-smile.

"I thought you could use them to switch up your wardrobe," Steve continued. There was a twinkle in his eye, an actual twinkle.

It was too late to play it off, but that didn't mean Tony wasn't going to try. "Sorry, Cap...these just won't go with anything I own. They're really more your speed."

Tony casually tossed the box onto the island in Steve's direction. Steve picked up his plate of food and backed away toward the large dining area. "So you don't have a pair. I really did figure out what to get for the man who has everything."

"Nice job, Cap," Barton commented, picking up his shared plate and following Steve over to the large dining room table.

Natasha didn't say anything, she just gave Tony a knowing glance. What she knew exactly was a mystery, but she was clearly on Steve's side. She slid gracefully off her stool, joined the others and resumed eating her eggs.

Tony glared at the box of socks on the island. Ambushed. He'd been totally ambushed - and now he was surrounded by conspirators. Left alone with the Grandpa socks. This would not stand.

Second Rule of Engagement: Find a good hiding place.

The first time Tony tried to return the Grandpa socks he simply slipped them into a bucket of Steve's laundry. In spite of having access to all of Stark Industries employees, Steve tended to take care of his own needs like housekeeping and laundry. So the next afternoon, when Steve was between loads, Tony took a walk to the laundry room and tucked the socks under the folded undershirts.

That night Tony found the socks neatly placed outside his bedroom door.

The second time Tony tried to return the Grandpa socks he made more of an effort. For his first attempt he hadn't factored in that of course Steve would find the socks as soon as he put his laundry away (which would've been as soon as Steve brought the bucket to his room because that's the way Cap rolled). Tony needed to find a place that would be much less obvious.

As a general rule, those living in the Tower did not have access to all area. Private living quarters were private unless invited in by the occupant. Tony felt like those rules didn't necessarily apply to him as he owned the building, but at the very least he announced himself before he barged in. Barging in was also safer that attempting to be stealthy around a master assassin and a sniper.

Tony timed his second sock return attempt to coincide with Steve's morning-workout-for-insane-people. It was brilliant because no one would ever expect Tony to be awake at that hour, much less functioning. Tony simply worked through the night in his lab and bypassed sleeping altogether. When JARVIS indicated that Steve left the building to go for a run, Tony meandered upstairs with socks in hand. He casually, oh so casually, let himself into Steve's quarters and headed for the dresser. Tony rifled a bit until he found the underwear drawer, and then not thinking too much about being in Steve's underwear drawer, shoved the Grandpa socks way in the back.

Happy with his successful mission, Tony left Cap's quarters well before the super soldier was due to return. He really shouldn't have been surprised to come face-to-face with two spies in the hallway.

Both Natasha and Clint were leaning against the opposite wall with their arms crossed. It really was kind of spooky how they mirrored each other when they did that.

"What are you up to?" Natasha asked with a quirk of her eyebrow, as if she didn't already know.

Tony held up his hands not quite in admission. "Just returning something of Cap's. Not planting any bugs or an evidence trail...that's more your speed, not mine."

"Those are your socks," Clint drawled.

"Not anymore!" Tony countered jauntily as he kept walking. Neither one of the S.H.E.I.L.D agents said anything else or tried to stop him.

Tony spent the rest of the day bubbling with anticipation. He hoped that Clint and Natasha wouldn't rat him out, but at the same time, if they gave Steve a heads up then he'd be that much faster to respond. Or…those socks could be stuck in the back of Steve's underwear drawer from now until the end of time.

Tony was not widely known for his patience – he wasn't known for having any patience at all – and the situation, although it was of his own making, was driving him crazy. He spent far too much of his afternoon Googling images of argyle socks, finding websites dedicated to argyle socks and locating argyle sock fan groups and spamming Steve's e-mail with all of them; Steve didn't acknowledge Tony's communication in any way. However, that night when they were all watching a movie, Steve put his feet up on the coffee table (his shoeless feet covered in a pair of grey and black argyle socks) and Tony just knew Steve was mocking him.

Damn it!

The next morning after breakfast, all of the Avengers other than Thor who was visiting with Jane, gathered in Tony's lab for a demonstration of his latest alteration to the Iron Man suit. Clint did not have fond memories of being hoisted by his pants to the top of a building during the battle of New York and had requested a modification that would allow a handhold or something that would allow him or Natasha to latch on to the suit instead of being carried. Not only would it be more comfortable for them, but it would also leave Tony's hands free to be used as thrusters or weapons.

Both Natasha and Clint were suited up with the addition of a lightweight harness Tony wanted to try with the modifications. As the suit was flying and being pieced together around him, Tony was mentally rehearsing a quip to say when he landed for his big finish. But when his feet touched down on the platform all that came out was, "What the hell is that?"

Tony shook out his left foot. Something was definitely wrong. "JARVIS? What is that?" Tony demanded.

"I believe it is a sock, Sir."

Tony wheeled and glared at Steve through the armor's faceplate. He didn't know what was worse – that Steve had so brilliantly responded, or that he somehow managed to get JARVIS' assistance when he did.

"Actually, it's a pair of socks," Steve corrected with a grin. "Grandpa socks."

Natasha nodded in approval. She was very proud of her fledgling. Barton held his hand out for a fist bump which Steve returned without dropping his gaze from Tony's. Bruce was bemused.

Steve raised an eyebrow obviously trying to channel Natasha, but he couldn't prevent a laugh from escaping. It was an honest-to-goodness laugh. Not a put-down laugh at Tony's expense; not an "I don't really get the reference so I'm going to chuckle to make you think I know what's going on" laugh; but a genuine, "I played a harmless joke and I really got one over on you" laugh. It made him sound unexpectedly young.

It was that laugh that loosened something in Tony's chest. Instead of being angry that Steve had co-opted JARVIS (which probably wasn't difficult at all because JARVIS had a thing for Steve and his old school manners), Tony instead felt a thrill that Steve had been willing to play. And the fact that Steve targeted Tony as the one to play with – that felt important too. There was something new and fragile that was at a beginning here, and Tony wanted to give it space to grow.

With a *snap* Tony's faceplate lifted. "Oh, it's on, Rogers," he replied with a grin that was at odds his serious tone. Then he stalked over to where Steve was standing and grasped the younger man's forearm for balance as he stuck out his left foot and started yelling instructions to JARVIS about removing the boot. Dummy was quicker than Tony in retrieving the boot and delicately reached inside to take out the offending socks, but instead of placing the socks neatly on the work table as requested, Dummy started waving them like a flag and raced away to the far reaches of the lab.

With a roar and threats of dismantling Dummy into spare parts, Tony strode after the wayward robot. Oh yeah…it was on.

Third Rule of Engagement: Keep 'em guessing

For the next few days the Grandpa Socks traveled back and forth between Tony and Steve. Steve found the socks in his gym bag. Tony found the socks in his coffee mug. The handlebars of Steve's motorcycle got new argyle grips. Tony's vast tie collection expanded to include two new argyle additions hanging neatly with the rest. But after the stunt Steve had pulled off sneaking the socks into his armor, Tony wanted to get a little more creative.

That was how Tony found himself in the kitchen waiting for Steve to cook breakfast once again. The whole morning thing was becoming routine and if that didn't say something about his change in lifestyle than nothing did. On this particular morning Tony had convinced Bruce to join them; even Thor, who was earth-side, was present in the kitchen. It was far too obvious that Tony had something planned, but he couldn't resist gathering an audience to watch what happened.

It was funny to watch Barton and Romanoff try to predict where the socks were by observing Tony and waiting for a tell. He tried to overcompensate and throw them off by being extra twitchy. Steve was going about his routine, attempting to ignore the crowd and pretend nothing was amiss, but he was cautious when he opened cabinets and drawers. The whole room was tense with anticipation.

"And what is the purpose of this game?" asked Thor leaning against the counter closest to the stove.

Bruce took a sip of his tea. The Asgardian had enough trouble understanding Midgardian customs; this sock silliness was almost beyond explanation. "Ah, I think what they're doing is along the lines of a game we play here called Hot Potato. If the 'potato' gets passed to you, you have to pass it along as quickly as possible and not get stuck with it."

Tony smiled smugly and blinked furiously when Steve opened the cabinet with the pans just to see what Natasha would do.

"Ah! It is a children's game!" Thor's grin was boyish. He was a fan of all types of contests and games. "We played a similar game, but it was not as popular as a game from my youth called skinnleikr. Four children would stand at the corners of a square and toss a ball or rock around keeping it from the fifth child who tried to grab it."

"That sounds more like Keep Away," mused Natasha narrowing her eyes on Tony but not falling for the excessive blinking trick.

"Or Monkey in the Middle," added Clint whose eyes followed Steve.

Having gathered all of the hardware needed for making the meal, Steve reached for the handle of the refrigerator. Tony had no idea what body language gave him away, but both Natasha and Clint became hyper focused on the fridge. Steve must've noticed a change in the air because he tossed a glance over his shoulder. Natasha gave him the slightest chin nod and a smile ghosted over Steve's lips.

Giving up all pretense, Steve flung the door to the fridge open wide and stepped slightly to the right. The wide open door gave Clint and Natasha, who pushed herself up slightly off of her stool while leaning on Clint, the best view. Even Thor leaned forward avidly searching for a sign of the Grandpa socks. Bruce glanced over at Tony who hid a grin behind his coffee mug.

The elusive socks were not immediately evident. Steve's glance at Clint confirmed that the sniper didn't see anything out in the open, so he just went about gathering eggs, bacon and cheese from their various positions. If the socks were hidden in the back somewhere, Steve wasn't going to give Tony the satisfaction of watching him search for them.

However, it was clear to the observers that Tony was still on edge, gleefully waiting for something to happen. Steve got the bacon going in one pan, and then brought a large glass bowl and the carton of eggs to the island counter. Steve flipped up the lid of the egg carton revealing twelve pristine eggs; no argyle in sight.

Steve reached for the first egg in the carton; Tony twitched. He couldn't help it. He trained his gaze on the ceiling feigning nonchalance and failed miserably. Steve chuckled and examined the eggs more closely but they didn't appear strange. With a shrug, Steve grabbed the egg he'd originally reached for and expertly cracked it one-handed against the edge of the bowl.

The resulting crunch was unusually loud in the abnormally quiet kitchen. And out of the egg slid a sunshine yellow yolk surrounded by the rest of the egg's slimy innards. Natasha eased back a bit. She looked genuinely disappointed; as did Thor. Steve glanced at Tony, the smile that was hinted at before bloomed in earnest on his face; his hand hovered over the remaining eleven eggs.

It was a good thing Tony had the Iron Man mask to hide his face most of the time because he was apparently awful at keeping his thoughts from racing across his face. Steve's hand moved decisively to the middle of the carton and picked up a second egg. This time when he cracked the egg against the bowl the shell shattered in a shower of shards surrounding tan, brown and blue argyle socks which exploded out of his hand and flew in two different directions like spring coiled snakes from a peanut brittle jar.

There was a collective exclamation of surprise as Steve stepped back to watch the socks fall. Clint caught one and the other landed on the floor at Thor's feet. Tony was overwhelmingly pleased with the success of his surprised and the laughter it generated. He could've done without the shoulder numbing clout on the shoulder from Thor when he exclaimed with approval, "Well done, Metal Man!" but you've got to take the good with the bad.

Laughing and shaking his head, Steve collected the socks. He held them out toward Tony, not to hand them off but just to ask, "How did you do that?"

"I vacu-formed a plasticine egg around the socks!" Tony gleefully shared. "Do you know how hard it is to make a pair of socks fit into a shell that size?"

"Is that what you've been doing this week?" Bruce inquired. "With all the yelling and the cursing and explosions?"

Tony laughed and shook his head in the affirmative. He looked around the kitchen, pleased with the vibe that he'd created. Bruce was drinking his tea, smiling and relaxed. Thor was helping Steve clean up the mess of plastic shards while demanding to hear the exploits of the Grandpa socks from the beginning. "Such a tale as this is meant to be shared!"

Natasha and Clint were more reserved in their reactions until Clint held up his fist and said, "Nice job, Stark!" Tony returned the obligatory fist bump with pride, feeling once again that he'd stumbled into the start of something new. Natasha's eyes warmed at the exchange and all at once it was too much, Tony had to look away.

Tony smacked his hand down on the island counter, "Are we going to sit around talking about socks, or are we going to have something to eat? I think Cap was cooking us breakfast…"

Steve threw a slice of bread at his head which Thor, already in a gaming mood, took as an invitation to a food fight. There was a lot more than plastic shards to clean up when it was all over.

Fourth Rule of Engagement: If you can't beat 'em, join 'em.

After the "Argyle Egg Explosion" and ensuing food fight, the game with the Grandpa Socks was no longer confined to Tony and Steve. Steve surprised Tony by "gifting" the socks to Clint next. The archer seemed surprised and shyly pleased to be included. Tony would've thought Steve would tap Natasha next. But Cap had more experience with team building and by including Clint he automatically included Nat.

Tony got the socks back attached to a Nerf arrow because Barton wasn't allowed to use his real arrows outside of the training area. Let's just call that a lesson learned.

Bruce was the next to receive the socks. A box marked "Super Special Lab Delivery for Dr. Banner" arrived on a Tuesday afternoon. He left the box unopened on his desk until Friday just to make Tony crazy.

Natasha unearthed the socks in a box of Cracker Jacks on movie night.

Thor found the socks wrapped around Mjolnir's handle.

Sam was hit in the head by the socks made into a ball and thrown by Thor. Then they had to explain that Thor was supposed to hide the socks or leave them somewhere the person could find them, not just randomly throw them at people. Thor liked his method better and taught everyone how to play skinnleikr.

Everyone had distinctive styles of play: Clint usually delivered the socks via arrow or similar transport method. Bruce was methodical about sock delivery and could take days to work out a deceptively simple plan, while Natasha never had the socks in her possession for more than twenty-four hours. Tony tended toward elaborate machinations and Steve liked to work with a partner.

Tony tried not to take it personally that Steve had teamed up with everyone else, even Pepper, at least once, but not him. He knew his own party line – "I'm not a team player" – but he thought that maybe those days were over and maybe things could change. He basically turned his tower into a gigantic clubhouse for crying out loud! Not that it really mattered; the last time he saw the socks Clint was mumbling over then and unless Tony was on his hit list, he'd be out of the loop for a while.

So Tony was surprised when Steve showed up in his lab later that day socks in hand.

"How's it going, Cap?" Tony asked. "I see you got your socks back."

The right side of Steve's mouth quirked up in a grin, but he didn't lose the contemplative look on his face. He leaned against the doorjamb of Tony's lab and held the socks up as he caught Tony's eye.

"Can you make them fly?"

Tony grinned and waved him in. This was gonna be fun.