Kisses are what define the relationship between Tony and Steve. Each kiss means something different to them. Some of them are emotions that can't be conveyed aloud while others are messages sent through physical contact as opposed to verbal communication. It is their language, known only to them, and that is what makes every kiss an important one.

Some kisses are small pecks on the lips. These kisses are meant for goodbyes, also known as the 'energy-givers'. They seal a promise to work hard and come back safely. Whenever Tony goes on a business trip, Steve grasps the back of his neck and steers him into the shortest of kisses before sending him out the door. And to Tony, it is almost a curse to leave without one.

Some kisses are long, not giving energy, but taking. These kisses are a way of expressing longing, loneliness, and the ache of missing as well as the need for comfort and reassurance. On a day that Steve came home from a two week long SHIELD mission, Tony was on him before he was even through the door. They relished in the returned contact and kissed and kissed and kissed. In fact, these kisses are sometimes the most passionate, and they don't stop until all of the barriers between Steve and Tony are gone and they are laying in a tangled mess underneath their cool bed sheets, struggling to reclaim the breath that had been lost during their love making.

The kiss that usually follows is the goodnight kiss. These are lovingly applied anywhere on the upper body, sometimes a cheek, the lips, and even occasionally the neck. They are soft and tired, a quiet way of saying 'I love you' and 'I'll still be here in the morning'. Tony forgets these kisses more often than not, but Steve is there to make up for it. Every night as they lay in bed together, Steve leans forward and kisses Tony right behind his ear. There is no particular reason as to why he leaves it there, but Tony never minds. And though he would never admit it, the kisses made him feel safe, if the arms wrapped tightly around his waist did not.

And while Steve takes care of goodnight kisses, Tony is all about giving the good morning kisses (that is, when he is actually awake and not zombified). On early mornings that he wakes up rested before Steve, he'll wake him up with kisses that cover his face and make him snort and try to push Tony away. When Steve warns him about his atrocious morning breath, he makes it a point to breathe heavily in Steve's face, leading to him being shoved to the other side of the bed once the smell hits Steve's nose. It's completely immature, but it gets him laughing, and come on, it's part of the Stark charm.

There are also the kisses that don't fit into a certain category, ones that aren't as simple as day or night, hello or goodbye. There are the biting kisses that accompany anger, the teeth-clashing kisses that are reckless and eager. The kisses that are more tongue than lip, that take Tony's breath away and cause Steve's eyes to flutter shut. The kisses that Tony trails down Steve's body, undoing him with every single one. The kisses Steve places on the very insides of Tony's thighs, which are incredibly intimate and Tony's greatest weakness.

All of these kisses are familiar and well known to both of them, but there is a single kind that is never talked about. It is one that they wish they never have to have or need. This kind of kiss is what keeps them together when they are falling apart. This is a dreaded kiss, and yet it's so completely necessary. Desperation. Love.

-X-O-X-

It was only supposed to be a simple press conference in Seattle. They'd be in and out, staying just long enough to have dinner before flying back to New York. The flight to Washington was relatively smooth, and everything was going just as planned, until several explosions shook the plane and it crashed messily into the ground below. It happened so fast that the last thing Tony could remember was jolting in his seat, trying to seek out his teammates after the hit.

Tony awoke to someone shaking his shoulder and slapping his face. He struggled to peal his eyelids open and focus on the person in front of him. Though his vision was blurry, he could tell from the bright red hair that it was Natasha. Just as his sight began to fix itself, the ringing in his ears began to die down as well, or at least enough to hear what Natasha was saying to him.

"Come on, Stark, you have to get up, we've got to find the others. I tried to contact SHIELD, but my communicator is busted."

Tony opened his mouth to speak, but was cut off by a coughing fit. Natasha hastily rubbed his back as he doubled over and hacked his lungs out, his body attempting to filter out the harmful smoke he'd inhaled. He was given a moment to collect himself before Natasha grabbed his arm and helped him stand up out of his mangled seat.

Though he didn't trust his legs to hold him up or his mind to collect itself, he shrugged off Natasha's grip and snatched her communicator, holding it a few inches in front of his face. It was banged up, but as far as he could tell, it wasn't broken. "Huh, it looks fine. I'd say all it needs is a charge. If you have your Widow's Bites on you, you could use a bit of that energy to power this up."

The redhead gave a jerky nod, stealing the communicator back and holding it in her fist. "Alright, well, it has a tracking system in it, so if we can get even that working, we'll be fine. I'll fix it, but Tony, you have got to find—"

"Hey."

Natasha whipped around midsentence at the voice she knew so well. She swore under her breath, her shoulders sagging as relief washed over her. "You're alive. That's good. That shoulder looks pretty bad, though."

Clint shrugged, wincing as he did so and cursing his mistake. He limped over from the wreckage a few feet away before stopping and looking around. "Damn, we blew out half a forest with this thing. And yeah, this shoulder hurts like a bitch and is bleeding a lot, but we can use my shirt as a tourniquet. Anyway, I found Bruce. He's unconscious, which is some kind of luck, and he's not looking too bad. He has a scratch here and there, but at least he's not big, green, and angry."

"The last thing we need is our Monster tearing up what's left of these woods. The conservationists will go nuts," Tony chuckled, absently rubbing an eye with the back of his hand.

Natasha and Clint looked at each other silently, a morbid seriousness in their expressions.

Tony didn't seem to be paying much attention to them, though, as he was struggling to help his brain catch up with what was going on. "So we've got the two superspies, Bruce, the rich guy (me), and…. And…Oh God…" His hands began to shake as he fumbled over his thoughts and went over the team's attendance again and again. There was one person missing.

Before he could stop himself, he was scrambling through the wreckage in a pure panic. He tripped and stumbled as he went, causing hot spikes of pain to shoot up his legs, but he ignored them. The plane ride was beginning to come back to him and he remembered; he remembered—

"I'm going to go in the bedroom and read. You're welcome to join me," Steve's voice was soft and even, a hint of humor and suggestiveness in his tone.

Tony glanced up briefly from his StarkPad. "Hmm? Nah, I prefer it out here. Besides, I'm sure all I'd do is bug you."

"Well, if you're sure." An affectionate smile grew on Steve's face and he leaned forward to kiss Tony's forehead and ruffle his hair before heading to the back of the plane.

Tony could feel his heart squeeze in his chest. That was right. The reason he had been looking for the other's when the plane was hit was because the seat next to him was empty. And the back of the plane was where…

No. No. No. Tony catapulted over broken walls and random pipes and wiring, trying to guess where the bedroom had been. He urged his feet to carry him faster, and when the blur of a figure appeared in front of him, he couldn't stop, running straight into a broad chest. He bowled the man completely off his feet and they fell together in an undignified heap.

Rough hands grabbed his face, forcing him to look up. Steve was wearing a worried expression, his eyes tracing Tony's face. "Jesus, Tony, you're ok…"

He wanted to speak, to say a million things to Steve. But in that moment, he couldn't find the words to say. So instead of talking, he reached up and took Steve's face in his hands, pulling him forward and crashing their lips together. It was a messy and uncomfortable kiss, but it conveyed all the words he wanted to say but couldn't. I was so worried. You're safe. Thank God. Don't ever scare me like that again. I love you.

-X-O-X-

Steve and Tony are two people who are not afraid to speak their minds and give their opinions. They can talk a lot and make themselves heard. They can bicker and argue incessantly, and they do so a lot. But at the end of the day, the important things are expressed through their kisses.

And these kisses aren't at all like the ones Tony plants on Pepper's cheeks after a board meeting. They aren't like the ones Steve and Natasha exchange after spending the afternoon sparring and wearing each other out.

No, these kisses are different, no matter if they are common or rare.

Tony thinks about them sometimes; he wonders what it is about them that make the kisses so special. But when Steve gets down on one knee and slides that ring on, kissing the top of his hand after doing so, Tony doesn't find himself wondering anymore.