He starts slightly as the door to the lab opens and then closes without warning. He tears his eyes away from the mess of notes spread out before him that were in an order to his eyes only to glance up to find the source of the disturbance.

Something jams in his mind as he realises the reason for the tension that has begun to shift in the air around him, apparently without cause. But there is one. They're alone now. Maria has left them quite alone together.

His brain, still struggling to process the enormity of something that should not have been, sluggishly attempts to fumble for an excuse to follow suit but before he can his eyes fall on her and somehow he reaches an entirely new level of hopelessness where this situation is concerned.

She's perching innocently, with a flicker of daring and confidence because she knows damn well he would never allow anyone else to do this, on top of the workbench opposite him. Her legs are draped lazily over the edge, swinging backwards in forwards in a set, comfortable rhythm, like a metronome gently counting out the seconds that trickle between them in ever tautening silence.

Her hands are the only give away to the fact that she's not altogether unaffected by the tension that still twists and pulses between them. It seems that she too can feel the ripple and crackle and slight strain that's sprung up between them in the absence of their colleagues. Their reasons and motivations to hide whatever it is that's between them now have evaporated with them and those things they had hidden so successfully before have flooded back now, as though Maria's departure had been the final push in the bursting of a dam.

Her fingers are curled under the lip, her knuckles white from the strength of her grip and his eyes dart down to this one slight piece of treachery that her body offers to his knowing glance, before flicking back and connecting with hers almost at once.

It's only that tiny betrayal in her hands that gives her away to him, however. The rest of her is as exquisitely composed as ever. Calm, appearing to be in her element here though he knows that this lab is far from it, particularly now she's found herself in present, particular company alone with him again.

She's looking at him with that way she has; as though she knows every secret he has ever kept and every dream he has ever had and every endless though that burns itself out flashing through his brain, focussing increasingly on her and the exact shape and curve her body makes as she tilts herself towards him a little.

A dull flush creeps up his neck at this; more so when her lips quirk into a playful smile, seeming to confirm his earlier suspicions of her knowing precisely what he's thinking at any given moment.

He takes a deep breath and then a few steps towards her, moving around the table that had been separating them, leaving nothing between them now but taut air and tension. He doesn't know why he moved, why he exposed more of himself to her, why he feels like he's stripped himself bare by simply moving closer to her, why he went out of his way to remove the one physical barrier that kept him from her.

But that's the problem with her isn't it? He has no idea why he's so drawn to this woman, why she pulls him in so much and why she seems so drawn to him in turn. Made all the more inexplicable when he considers that he knows how this would end. And surely she knows how this would end. And there's no sense to it, no rationale, no reason that he can find but there's something undoubtedly magnetic in them that neither of them seem able to fight or escape despite their better judgement on the matter.

He pauses in front of her, his hands murmuring over one another, his fingers threaded together, squeezing and twisting and tugging and trying to get a grip on something, anything. Anything other than the thoughts that are beginning to fill his mind.

It's been three days now. Three days since it happened. Three days of confusion and conflict and unbearable temptation. Three days of wanting her, of wanting to see her, wanting to speak to her, to set things straight, to settle things. Three days of avoidance and excuses and humiliating fear of what might come preventing him from doing so.

And now here they are. Fate it seems, has conspired with something else far deeper that he can never hope to pin down to put him into this position he had somehow, foolishly, childishly, thought he might escape.

And his head is filled with nothing now, nothing but her, and him, and them that something seems so certain to want to be but he knows never should.

"I'm fine." She tells him firmly before he's even opened his mouth to say something he's sure he would have thought of by the time his tongue got around to forming words.

Her eyes find his and bore into them making a good show of honesty because no-one could ever accuse those eyes of trying to convince them of anything that wasn't some sort of gospel truth.

Yet he knows the woman behind them too well to be taken in by that alone. She's swaying slightly where she stands in front of him and so he knows better than to take her at her set and steady word and her unfaltering gaze.

He ignores her, as expected.

His only response to her insistence that she doesn't need any help is to glance down pointedly at the scarlet stain of blood soaking her neck from a cut under her hair she'd hoped to hide from him for long enough to stop him worrying. Though it seems he'd been doing plenty of that before she ever arrived back at base injured.

"It's just a scratch." She reassures him, a little too casually it seems from his look of reproach, "It's fine." She insists easily, hoping repetition of her earlier words would somehow work better at driving their meaning home.

It doesn't.

"It won't take long for me to make sure then, will it?" He replies simply but firmly.

There's a certain protective streak in him, not to mention a healthy dose of stubbornness that she always seems to underestimate and play down to herself from the generally calm and relaxed atmosphere that somehow shadows him and puts her at ease with him. Too much ease, she reminds herself for the umpteenth time.

She glares at him and he steadily and obstinately holds it, calm and gentle. He doesn't push back at all, he simply absorbs her frustrations and irritability until he catches something flickering her eyes and she groans. She's exhausted and vaguely dizzy now she comes to think on it, she has no interest in wasting energy on something so pointless as letting him settle his worries checking her out.

She sighs and lowers her gaze and her defence, the almost permanent barriers that block her from the world reluctantly crumble at her urging and she relaxes her posture, slumping forwards slightly and giving him permission, letting him in.

He takes another step towards her, closing the distance between them entirely. He slides a hand to her waist and ducks his weight under her, supporting her and steadying her. There's something about him that settles her, some equilibrium the pair of them reach that makes her far more comfortable with him than she would be with most. Especially given the history they share. Though it feels more and more like that every day; history, quickly becoming ancient.

Her breath is hot against his skin as he takes a moment to meet her eyes and capture her focus, even if it is only for a second. He hopes he hides his worry for her better than he thinks he's doing. He doubts she'd appreciate him worrying for her, she'd consider it a distraction or a luxury they couldn't afford but there was something inherent in his nature that the threat of her disapproval could not quite sway.

He huffs impatiently at the awkward position of her wound and the way that, like its owner, it seems intent on preventing him from examining it. Without thinking about it, he slips his hands around her waist and lifts her into his arms, pressing her body momentarily against him before he gently lowers onto the bench beside him.

He releases her quickly, trying to avoid flustering himself after the sudden contact and to avoid thinking about how warm and soft and welcome she was against him. She distracts him by pointedly raising her eyebrows at this, no doubt seeking to remind him of the way he had irritably shooed Tony from perching on the workbench a few days before.

This implication of some sort of special treatment for her does nothing to assist with the flush of hot colour that's spreading up his neck and into his face.

He clears his throat and attempts to compose himself, trying a distraction method of locating the first aid kit he's sure is squirreled away somewhere nearby. As he hunts, he answers her unasked question.

"Desperate times, Ms Romanoff. " He murmurs distantly to her, ducking under the bench now at his back and wrestling a small first aid kit from it, thinking how laughable the action must be when she's just returned from something that must resemble a war zone. Still, any port in a storm...

He comes back to himself at the sound of her voice.

"Natasha." She corrects him pointedly.

His eyes flick to catch hers for a second, wondering how he seems to have developed something of a knack for sparking fires in the fleeting glances he sends her way every now and then.

"Natasha." He nods in absent agreement, fumbling for the switch to turn on the light above her head to afford him a better look at her injuries.

He steps closer to her, his hand brushing over hers and hastily darting away as though afraid she might burn away to dust at his faint touch. He braces it finally on the bench beside her leg, agonizingly aware of how close she is.

He leans forward and tenderly brushes her hair away from the wound with another quiet apology as she winces slightly, her hands gripping the edge of the workbench a little more tightly, biting her lip to suppress a sharper growl of pain that she knows will upset him more.

"I didn't think you were the right kind of doctor for this." She observes lightly, trying to distract herself slightly from his examination, gentle though it may be.

The pointed inflection she lays on his title causes him to reply with an absent, reflexive, "Bruce." And a soft smile touches her lips at that while he processes what she's said.

He catches the faint spark of amusement stirring in playful eyes in front of his as he looks towards her and presses his glasses further up the bridge of his nose before he says quietly, "I'm not, no, but I, I just had to check...To be sure...If anything had happened to you, Natasha."

His hand has come to rest gently on her cheek, trembling slightly as he speaks. He holds her gaze unflinchingly which surprises her and causes the weight and the poignancy of his confession to hit her all the harder.

She wants to tell him that he doesn't have to worry about her or fuss over her. She wants to tell him that she can take care of herself. But he knows that. She knows that he knows that because he knows that's why she came back; because she can handle herself. He's not telling her not to leave, not telling her to let him take care of her, let him protect her, let him do her job for her; like so many others. He's telling her that if a day comes when something does happen, when the skills he knows she possesses aren't enough, he doesn't know what he'd do.

Something softens in her and sincerity slides in behind her eyes, darkening and deepening them all at once.

Her hand fits softly over his, giving it a soft squeeze, drawing his eyes to hers once more as she says quietly, "I'm okay, Bruce."

Her thumb gently brushes over the back of his hand, seeking to soothe and reassure. Her eyes refuse to leave his, holding his gaze with a fire that consumes and creates all at once and dares him to look away from her all the while knowing he can't.

She's mere inches from him now. He can still feel the soft flutters of hot breath from her lips brush against his. Ironic, as he seems to have forgotten how to breathe himself. And his heart hammers so hard against his chest that he's sure she'll hear it, feel it if she comes any closer.

Her smaller hand squeezes his larger one, curling around it and holding fast, seeking to comfort, to anchor him to her and the reality that she seeks to reassure as she murmurs, "I'm here, Bruce, I'm right here."

He nods. His eyes, unable to tear from her, something filling him up as he looks at her. And her touch has inspired something in him. Fire flares through his nerves heightening every sense. Electricity cracks like a whip through his bones. Lighting his soul as it flashes through him.

Something is burning inside him that he can't explain and doesn't need or care to. In this moment he's caught himself in with her he doesn't need or care to explain a damn thing.

It snaps. Whatever fragile thing has been holding him back for her all these weeks has finally shattered here and now. Before he can consider what or how or why, questions that seem so pointless in this moment when she looks into his eyes like that, when she makes him feel the things she makes him feel with a simple look and he craves her touch, her kiss, her, more of her, all of her.

And he's kissing her. He's kissing her softly and slowly and almost shyly once his lips crash against hers. She tastes sweet and smooth but with an edge that kicks like fire, like liquor, like heaven and hell and angels and demons and everything and nothing in between that he was never able to handle and yet he's the only one that can.

And she's kissing him back now. And everything he is and everything he was and everything he would be could cease right now in this moment and he wouldn't care. He would welcome it almost. Because this feels right; however much he'll curse himself for it later and swear it was a mistake and he should never have let it happen, it feels infinitely, eternally right here with her.

Now feels right.. Now with his lips against hers and his hand at her waist drawing her in closer and her fingers dragging through his hair; now he feels like he could live a thousand lifetimes in this single second and still never want it to end.

But it does. It has to. Eventually. It can never last. Not for him. Not with her.

He slowly pulls away from her and breaks the kiss, taking every shred of self-control he possess to do so and not do what he's aching to and hold her close in that moment feels indescribably harder than holding back the monster within him that scares him so.

Her eyes slowly flutter open as she registers what's happening and he can read the comprehension dawning in her eyes but little after that as she shuts down and hides the emotions she feels from him.

Both of them are breathing hard even as they both retreat slowly, tentatively back in on themselves, their guarded eyes meeting in the middle once more as they look up all at once.

And he knows that he'll remember the look that's blazing in her eyes right now until the day he dies.

He takes a deep breath, glancing up at her again before he slides his glasses from his eyes. His fingers nervously play with them out of habit more than anything else as he struggles to say, "Natasha, I...What happened between us before, in the lab, after, I mean..."

"You kissed me." She says simply, something gentle in her voice despite the bluntness of her words.

"I, I did." He agrees, dropping his gaze, having no idea what to say to her. But she again makes him finding something to say unnecessary as she prevents a lull in the conversation herself.

"And I kissed you back." She adds quietly and he looks up and meets her eyes again despite himself.

He swallows with difficulty. His mouth feels as dry as sand when he finally says, "You did."

He pauses a beat and she fills it by raising an eyebrow and prompting evenly, "But..."

She knows. He's sure. She knows what he's going to say, what he wants to say, what he has to say, and probably why. She always seems to know everything before he does; even before he thinks it sometimes. She knows him. And he knows her, he supposes, because he always knows when she knows. But regardless of that, he feels compelled to actually say it anyway, to finish what he should never have started.

"But it, it can't happen again, Natasha." He murmurs softly.

A faint, humourless smile tugs at her lips and she closes her eyes, being the one to break eye contact between them for the first time as she does so. "I thought you'd say that." She breathes tonelessly, confirming what he'd already guessed to be true.

There's steel in her eyes when she meets his again, a defiant challenge in them daring him to look away. He doesn't. He wants her to see him, wants her to understand, needs her to understand him now.

"Because you know it's true." He tells her feebly, without any real conviction in his voice.

The look she's had in her eyes from the start tells him she's not going to make this easy for him.

"No." She says flatly.

He resigns himself as she slides from her perch on top of the bench and steps towards him until she's almost offensively close to him before she informs him firmly, "Because I know you Bruce." She pauses a moment, her eyes quietly searching his before, "You're scared." She breathes softly, her body and her poise relaxing just a fraction, just enough for him to notice.

She's not naive, he knows her too, knows her well-enough for that, but she's stubborn, infuriatingly so. He irritably pushes back his frustration, though some of it snaps into his voice anyway as he shakes his head and says, "You should be." He breaks off for a moment, irritated with himself for letting his control slip. He closes his eyes, massaging the bridge between them, wishing she wouldn't make this so difficult.

"I could hurt you." He manages to croak to her finally, his voice breaking at the thought, at the memory.

He wonders how she can have seen that, have gone through that and still, still...

She's quiet, giving him the moment he needs to ground himself in the reality of this conversation again before she says softly, "I could hurt you."

The air he hadn't realised he had been trapping in his lungs bursts from him in a dull, bitter laugh before he said, "Yes, but you can control that."

Her voice is quieter than he expected, and so gentle it startles him as much as it would have if she'd suddenly screamed at him. "That's what really scares you isn't it, Bruce? More than losing control; surrendering it, giving it up and giving someone else that power to hurt you."

He swallows hard before he says shakily, "Natasha, you don't understand."

"Don't I?" She shoots back, some of her normally impeccable composure fraying at the edges. She reaches up, cupping his cheek in her hand and making him look at her again as she says, "I'm scared too, for the same reasons you are." She murmurs.

Her candour, her honesty surprises and touches him as he sees the validity of it stirring in her eyes, "But I made my decision." She presses, making herself go on, making herself say everything she wants to say; everything he needs to hear, "I want you." She whispers simply, as if it's the easiest and most obvious thing in the world, waiting a beat before she says, "You want me."

He almost breaks. He almost gives in and gives her what she wants, what she knows they both want. But he still can't quite bring himself to. And so instead he snaps in a strained voice, "I shouldn't."

A soft, sad smile touches her lips at this point and she murmurs quietly, "Wanting not to want something won't make it so." His eyes flicker up to meet hers again as she adds gently, "But you don't have to." She pauses and gently strokes his cheek with her thumb, wordlessly coaxing him to look at her again before she breathes tenderly, "I trust you, Bruce." He shakes his head at this, closing his eyes again.

"Hey." She says, her tone sharpening firmly, "I know better than anyone what you're capable of, what can happen when you lose control. I've seen what you're afraid of-"

"That's my point." He interrupts tautly, unable to bring himself to look at her when he says, "I could have killed you on that Helicarrier, it's not worth, I'm not worth-"

But she roughly shakes her head and looks frustrated and almost impatient at his interruption. "I've seen..." She trails off, hesitating for a moment before she says softly, her eyes somehow managing to meet his again. Her voice is quiet and hoarse, "I understand because I know what it's like to look at yourself and be unable to escape the monster you think you are." He stares at her and he knows that she does understand, because he can see the same strange mix of guilt and fear and pain that twists constantly in his soul reflected in his eyes.

She steps in a little closer to him, her body inches from his, her breath hot on his cheek as she says, soft and sincere, "You deserve to be happy."

He smiles sadly at her then replies, in much the same way, "So do you."

"I'm trying." She answers, with a stab at one of her wry smiles, "You're not making it very easy."

"Natasha." He begins and she takes a moment to exult in the way his breath bends around her name.

"I know." She whispers, sparing him the necessity of struggling to try and properly express what he's thinking, "I know." She repeats, almost absently, "It's hard. But we've been avoiding this for months and I just, I need an answer, a decision, I need...I deserve to know what you're thinking and how, how you feel about me, how you feel about this, about us."

He considers this for a long time, feeling her body rise and fall gently against his as she breathes, and when he finally answers her, it's slow and careful and he weighs every word, "I just want you to be happy. And if you think that you could be happy with me, then I'd like to try." He feels something pang inside him as he watches the faint smile he'd inspired in her flicker and die at his next, broken words, "But I can't."

"You can." She insists, an almost desperate fierceness in her voice, "You can." She moves even closer to him, nothing separating them now but hesitation and doubt. "You need to learn to take a few risks or you'll never let yourself have anything."

"The last time I took a risk I exposed myself to record levels of gamma radiation and..." His feeble fumble in the direction of humour relieves some of the tension in her in a light laugh.

"This will work." She promises him softly. And he wants more than anything to believe her. He does, when he looks into her eyes like this. "I trust you." She repeats, her voice low and certain, "Do you trust me?"

"Yes." He answers her honestly, instinctively, without thinking.

"Then trust me." She coaxes quietly, "Say yes."

In answer, he kisses her, soft and slow and he feels her smile against his lips as she kisses him back.

A/N: I'm still very new to this pairing and so any and all feedback on this fic would be very very much appreciated. Thank you for reading.