Superposition

"How do you know if someone likes you?" Bruce blurted, unable to help himself. Thor and Jane looked at him in surprise.

"Bruce, my brother, do you have a potential suitor?" Thor exclaimed loudly, and Bruce dropped his head into his hands. The three of them had met for a quick coffee in a small café near Stark Tower. Bruce and Jane had become fast friends in the short time that they had known each other, and frequently exchanged notes and opinions on their various projects and research work. Thor, not wanting to be left out of what he called 'this Midgardian sorcery', demanded to come along too.

Jane, who actually understood human social convention, shushed Thor impatiently and turned to Bruce with wide, lit up eyes. "What happened? Who?"

Bruce bit his lip. "I'm not sure. I might be reading too much into it…"

"But Bruce!" Thor continued determinedly. "It is soon to be the day of Saint Valentine, an occasion for much feasting and merriment! I was reliably informed that on this very day, it is customary to reveal one's feelings to the object of one's longing!"

Bruce blinked in surprise. "Wait, what? It's nearly Valentine's Day already?" Jane burst out laughing, as Thor obliviously grinned, still proud of his knowledge of Midgardian traditions. "I swear it was Christmas, like, two weeks ago? Shit."

This changed a lot. Who leaves ambiguous but more than a little suggestive notes on people's desks the day before Valentine's Day as a joke? An asshole, Bruce supposed, but not even Stark would stoop that low. "I found this in my lab yesterday morning." He explained, pulling a neatly folded piece of paper from his pocket and setting it on the table.

Jane picked it up, read it, and almost managed to maintain a straight face. " 'Lithium burns red, copper burns blue, let the Hulk have some fun, and maybe you too. Love, Your Number One Science Bro' ?" Jane snorted. "But that- That can only be-"

"Tony." Bruce said flatly. "Poetry really is not his strong suit."

"Clearly, subtlety isn't either."

"So, what do I do?" Bruce asked. "Do I confront him, or…"

Jane shook her head. "No, wait for him to approach you. I mean, he's trying here, right? And if everything I've read on Stark is true, it never exactly looks like he's the one instigating the relationships- he just lets other people do the hard bit. The fact that he's making an effort… I'd give him this one, Banner." She advised, trying to hide the smile. "Unless, of course, you don't want to snatch a date with Tony Stark on Valentine's Day?"

"I can't really say I've ever given it much thought." Bruce lied through his teeth, trying to stop his blush giving himself away.

"So by that, you mean, 'Yes, I fantasise about it every night but never worked up the courage to actually tell him.'?" Jane asked seriously, and Bruce nodded sheepishly.

Thor, who had apparently completely tuned out of the conversation, beamed brightly. "The sky has ceased in its seemingly perpetual rainfall!" He proclaimed happily, and on that note, bounded outside. Jane sighed, threw a handful of notes down on to the table and followed the incorrigibly enthusiastic demi-god out of the café, calling goodbye to Bruce as she went.

Bruce returned to his lab that evening to find a note on his desk containing the fantastically original and witty line of, 'If I could rearrange the Periodic Table, I'd put Uranium and Iodine together!'. Bruce groaned. He wasn't used to dealing with this kind of attention, wanted or otherwise, and the fact that Tony a) was his best friend, b) had been the subject of Bruce's unrealistic dreams for quite some time now and c) was truly terrible at getting to the point without unnecessarily long winded attempts at seduction, was really not helping the case.

And to make matters worse, the idiot was nowhere to be found. Bruce really didn't want to leave this without being talked over until the morning, but it seemed that Tony wasn't giving him a choice. It wasn't that he didn't like Tony like that; he had long come to terms with his attraction to his best friend- long enough ago to accept that it was never going to happen, however much he wanted it to. But now, it seemed it was happening, and Bruce didn't know why he felt so uneasy; he should have by all accounts been over joyed at this outcome, but it just wasn't settling right with him.

He didn't sleep well that night. Thoughts of Tony fucking Stark and his diabolical mind kept Bruce up until the early hours of the morning.

Walking down to the kitchen the following day, Bruce half expected a half-naked Tony to jump out of a closet, scream 'Happy Valentine's Day!' and try to molest him in the corridor. Fortunately, either Tony was able to control his raging sex drive, or else he was otherwise engaged for the time being.

At least, that was what Bruce thought until he saw the multiple plates of food on the breakfast bar. A stack of toast cut into (what were supposed to be) love heart shapes and peanut butter. Three different kinds of eggs. A stack of pancakes and maple syrup. Fresh sliced fruit. Bruce frowned at the sight, and then tried to stifle laughter at the note left next to the pancakes: '9x - 7i 3 (3x - 7u) Solve for i'

Bruce, deciding to humour Tony's terrible attempts at seduction, solved the equation quickly and couldn't help but tut at the result- they were only getting worse. He had just grabbed the bowl of fruit when Tony sauntered in with excessively casualness, and a clear determination to keep a straight face.

"Good morning, Bruce." He said, grabbing a pancake from the stack. "Happy Valentine's Day. Did Pepper bring this over?"

Bruce sighed. "Cut it out, Tony." He said flatly. "I'm not an idiot." Tony flushed a little, but continued chewing in awkward silence. "Thanks." He added quietly.

Tony blinked. "Thanks? For what?"

"For breakfast." He explained. "And for everything else, too. For letting me stay here and for putting up with the Other Guy and-"

Tony shrugged. "It's not a big deal, Bruce. I've got some work to do, so I guess I'll see you later."

He was nearly out of the door when Bruce eventually mustered up the courage to call after him. Bruce jumped to his feet and started towards the door. "Tony, wait, I-" Tony turned back, and Bruce held up the note containing the equation, a questioning look on his face. "Do you- Do you love me?"

"Yes."

Bruce was shocked by the firmness of the answer, and Tony didn't look uncomfortable or embarrassed in the slightest, whereas Bruce wished a hole would open up in the ground and swallow him whole. "You love me? Seriously? This isn't some kind of sick joke, is it?" Bruce felt the urge- hell, he needed- to check, just one more time, that Tony wasn't messing him around.

"Would you be upset if it was a joke?" Tony said carefully, keeping direct eye contact with Bruce as he moved back into the centre of the room.

He knew the connotations of the question, and flushed a little at the bluntness of it. "Yes." He murmured. "I'd be heartbroken."

"You know what, Banner? I think my day just freed up." Tony smirked, and Bruce laughed. "I'm going to kiss you now."

Bruce nodded. "That seems like a reasonable idea." And Tony's lips pressed against his with unexpectedly gentle pressure. "Is that all you got?" Bruce smirked, teasing Tony playfully. The other man grinned back, and Tony moved in once more, but this time, his tongue thrust firmly into Bruce's mouth. Finger nails clawed Bruce's back as Tony grappled for a better position without detaching their lips. Bruce moaned, arching closer to the other man at the contact.

"Fuck, why haven't we been doing this for months?" He gasped, when Tony abandoned his mouth in favour of sucking bruises on his collarbone. "Fuck!" He could only grip Tony's shoulders like a vice as he was efficiently worked over by Tony's magical mouth skills. The sensations were all just too much for Bruce: Tony's rough lips harsh against his skin, paired with the wet heat of his tongue soothing the marked skin and the occasional sharp nip of teeth keeping him on edge. He couldn't help himself from grinding his hips down against Tony's thigh desperately, as his ministrations had brought him to almost completely full hardness.

"What happened to no fucking on the first date?" Tony murmured teasingly in Bruce's ear.

A flush spread across Bruce's face, but he tried to keep calm and come up with a suitably coherent response. "It's overrated." He said, slightly breathless, and Tony chuckled. "And besides, I think if we hadn't have been so damn oblivious, we would have had many dates before this already." He reasoned, impressing himself with his line of argument when the other man was so determinedly trying to tease him to death.

"Oh, that reminds me!" Tony pulled away suddenly, grinning maniacally. "Are you a sample of carbon? Because I want to date you."

Bruce groaned, and not, this time, from arousal. "Are you kidding me, Stark? For a self-proclaimed genius and playboy, you are so terrible at science related pick-up lines."

"Did I kill the moment?"

"A little bit." Bruce said coyly, and Tony sighed exaggeratedly.

"Well then, let's see what I can do to fix that." And his hand darted out and palmed Bruce roughly through the material of his trousers. Bruce thought his legs were going to collapse under him as pleasure surged through every vein in his body.

"T-Tony!" He protested weakly. "Bedroom?"

"I like your thinking, big guy." He smirked.

They managed to stumble into the huge room eventually, with only several short stops for hurried and rough make outs and mutual grinding sessions on the way, articles of clothing that had not managed to make it all the way upstairs strewn haphazardly through the hallways, until the final belt buckles are unfastened and dropped unceremoniously on the floor by Tony's bed. Clad in just their underwear, Bruce took the opportunity to explore the previously hidden expanse of skin exposed to him hungrily, making the most of his time to taste and touch.

"Tony, that's…" He murmured, when his fingers traced the scarred tissue and discoloured skin around the rim of the arc reactor, casting strange shadows across Tony's chest in the pale blue light. Tony winced, and Bruce drew his hand back. "Shit, sorry, did I hurt you?" Bruce worried, biting his lip.

"No, it's just… really sensitive… I'm not used to people touching it, that's all." Tony explained breathlessly. "Do it again? Please?"

Bruce let his hands wander back up to where man met machine, marvelling at the genius of the technology, and the beauty of the contrast between cool metal and warm flesh. "You're beautiful, you know that?" Bruce said quietly, but sincerely.

"It's disgusting. I'm disgusting."

"It's not. And you're not. It's a testament to you, really, Tony. You could have given up, but you didn't. And I've never seen a piece of engineering like it. It's unmatchable. You are a one of a kind, Tony Stark; an absolute fucking genius." Bruce said, planting soft kisses around the reactor and down his chest slowly between every few words. "I love you too, incidentally."

"Glad to hear it, I must say." Tony joked lightly.

Bruce's hands hovered at the waistband of Tony's underwear. "Can I…?" Bruce asked carefully, and Tony nodded, his head tipped back slightly. Bruce obliged willingly, and the final piece of clothing keeping the last part of Tony hidden from him was banished to the floor. "Fuck."

"That's the general idea, Banner." Tony said drily. "Although, you might wanna get rid of those at some point. Want a hand?" He grinned, reaching out quickly and pulling Bruce's boxers down around his knees. He hummed in approval. "I most definitely like what I see." Bruce blushed and tugged them off the rest of the way.

"Since I was the one who seduced you with terrible science jokes, I think this is the least I can do." Tony grinned, and flipped them over so Bruce was lying on his back, before lowering his head down and sucking the tip of Bruce's dick.

The scientist gasped, and Tony took it as a cue to take him in deeper, pressing his tongue against the vein on the underside of his cock. Bruce squirmed and moaned quietly, concentrating hard on not thrusting his hips forward and burying his dick in Tony's throat as he so longed to. "Tony, fuck!" He keened, as Tony placed his hands on Bruce's hips, pinning him down as well as he could from his awkward angle. Bruce was sure that he was gripping so tight, he was going to leave marks, but he didn't care.

Tony swallowed him deeper and deeper, until Bruce was wondering how much more he could take before he choked, but Tony seemed to be pretty confident. He bobbed his head slowly at first, finding all the most sensitive parts of Bruce within seconds and taking full advantage of them, teasing him persistently until he was close to the edge. It seemed, however, that Tony was just as good at reading the body language that shows when someone was about to come as he was at giving blowjobs, since every time Bruce was going to warn him he was close, Tony slowed down his pace just before he spoke, looking up at him with wide, lust blown eyes.

Bruce didn't know, and didn't want to know, where Tony had learned to suck dick like that, but he thanked them heartily. Tony did the most magical things with his tongue and Bruce seriously looked forward to experiencing them again sometime, but for now, he just really, really wanted all of Tony. "Can you… Shit, Tony, stop! I need- I need you in me. Now, preferably." He said hurriedly, blushing a little. Tony pulled off with an obscene sounding pop.

"I think I could probably be down with that." He smirked, reaching over to his bed side cabinet and pulling a small bottle and a foil packet out of the top drawer. "You clean?" He asked, waving the condom in the air.

Bruce bit his lip. "I don't know. I mean, yes, technically, but, the Other Guy… And the radiation… It makes things complicated. It's probably best not to risk it." He was blushing a deep red now, and Tony leant over a planted a kiss on his forehead.

"Hey, hey, hey, Brucey, it's fine. Better safe than sorry, yeah?" He said softly, before flipping open the cap of the bottle and squirting a generous amount of to his fingers.

"Tony?"

"Hmm?"

"I haven't… Um… Done this before." Bruce confessed.

"Never?" Tony sounded surprised, and Bruce rolled his eyes.

"Never ever."

"I'll go slow." Tony promised, and pressed his index finger against Bruce's entrance. "It'll probably feel really weird at first, but tell me if you want me to stop, okay?"

Tony carefully pressed his finger into Bruce, and he gasped. The feeling of the intrusion was exactly as Tony described it- weird, but not overall unpleasant. "You're okay to move, Tony." He prompted breathlessly, and Tony slid the finger in a little further, until it was buried to the knuckle, before sliding it out again, almost completely, and adding another finger. The sensation of the two fingers moving apart, being scissored inside him was unnatural, but surprisingly good.

"You okay?" Tony checked, and Bruce nodded. "Good, because I'm about to rock your world, Dr. Banner." He said, and thrust his two fingers deep, and bent them a little and-

"Holy shit!" Bruce screamed. Tony cracked up, and brushed his fingers against the sensitive bundle of nerves again, more gently this time, and Bruce writhed on the bed, his hard cock leaking on his stomach. "Tony, I- I'm ready, just oh my god please just fuck me!" He begged mindlessly.

Tony shook his head. "Gonna give you one more, okay? I don't want to hurt you." Bruce glanced at Tony's dick, mentally compared it to the size of two fingers, and decided that actually, maybe Tony had a point.

The extra stretch stung a little, but by that point, Bruce was so wrapped up in his own pleasure, he didn't notice it. Tony pumped his fingers in and out quickly, but still managed to hit Bruce's prostate on what seemed like every other thrust. A minute or so later, Tony pulled his fingers out completely, leaving Bruce clenching down on thin air, trying to get that full feeling back.

Tony tore the condom packet open roughly and rolled it on, before covering it with another generous quantity of lube. "You ready?" He said quietly, looking Bruce in the eye. Bruce nodded, and Tony's hands find their way back to his hips, holding him still as he pushed into Bruce.

Bruce was definitely glad that Tony had insisted on the third finger. It burned, even with the lubrication, and Bruce couldn't hold in the gasp. "I'm fine!" He said quickly, before Tony had the chance to ask. "I promise, I'm fine. You're just… Big."

Tony smirked, his face otherwise a picture of complete concentration. Bruce guessed he was trying to stop himself instinctively snapping his hips forward. "Tony… You're not going to break me. I'm not s-some delicate flower. I want- I want you, all of you, please, just-"

Tony thrust shallowly, experimentally, and matching moans slipped from both of their mouths. "More like that?" Tony asked, thrusting again, harder this time, and Bruce let out a very manly squeal as Tony's cock pressed against his prostate.

"Most definitely more like that." Bruce nodded vigorously. Tony's pace picked up, and he fell into a semi-regular rhythm. "Oh, fuck, Tony!" He spluttered, as a foreign hand began to work his own cock lying flat against his stomach. "I'm not gonna- Jesus Tony please oh mother of God do that again." He begged, when Tony timed a thrust against Bruce's prostate with a swipe of his thumb across the sensitive vein at the tip of his dick. Tony grinned in response, as if to say, 'With pleasure.' and obeyed, obviously pleased with his handiwork as Bruce's back arched, his hips lifting. "Shit, Tony, I'm gonna…" He warned.

"Go on, Bruce." Tony urged, staring at him with a look of total wonder. "Come for me."

That was all it took to send Bruce over the edge, coming in white spurts through Tony's hand and across the crumpled bed sheets. After just two or three thrusts more, Tony joined him, releasing inside his lover. "That was…" He started, sounding a little breathless.

"Amazing?" Bruce supplied, helpfully, wincing at the ache as Tony slid out of him carefully.

"Amazing is a really good word. I do pride myself on my ability in bed." Tony grinned, slumping back into the pillows, blissed out. "Because, you know… It's not the length of the vector that counts. It's how you apply the force."

"Tony?" Bruce groaned.

"Hmm?"

"Can you please, please, stop with the terrible science pick-up lines?"

A/N: The equation, in case maths isn't your thing.

Solve for i

9x - 7i3 (3x - 7u)
9x - 7i9x - 21u
-7i-21u
-(7i/7)-(21u/7)
-i3u
i3u

Hope you had a lovely Valentine's Day! Thanks for reading! :)

Love, C x