Work Text:
River was leaning against the doorframe of Lamb’s office, a deliberate imitation of the position Lamb himself had taken a couple of weeks earlier, back when all of this mess had started. Slough House was quiet now, emptied out for the evening.
In hindsight, if someone had asked River to explain how he’d ended up where he was now, he wouldn’t have known how to answer.
Undeniably, he’d always been good at making things more complicated than they already were. A skill honed from an early age, sharpened through years of failures, with Slough House standing as the most glaring example.
For the most part, River was fine with "complicated": it made life a little more exciting, at least, and it made him feel a little more alive. It also made him feel, with increasing regularity, like an idiot, as the Jackson Lamb living in his head liked to remind him.
It was almost funny how much of the commentary in his head had Jackson Lamb’s voice now. It made a certain amount of sense: River had always been fairly comfortable swimming in self-loathing, and who better to give that feeling a sharp, efficient voice than his beloved/loathed boss at Slough House?
After all, the real Jackson Lamb - crude, indifferent, lazy - was everything you never wanted to become and, at the same time, the most competent spy MI5 had ever produced. He was the kind of man who got inside your head whether you wanted him to or not. He saw things. He understood people in a way River both envied and resented. When Lamb tore into him, when he pointed out River’s blind spots with surgical cruelty, it hurt, but it worked. River learned, got sharper, better.
So, if River wanted to prove himself to Jackson Lamb, it wasn’t all that strange. He’d spent most of his life trying to prove himself: to his mother, to his grandfather, to Regent’s Park. Lamb’s approval was just the latest thing he’d learned to crave, and the one least likely to be given.
There was also the matter that Lamb, through his contempt, his infuriating foresight, his intelligence, kept them all alive. River could doubt many things, but not this: if things truly went south, Jackson Lamb would show up to pull River out of trouble. No shining armour, no white horse; just sweat and that disgusting Honda Civic. But he was there all the same.
If River had been a normal person - Christ, if Lamb had been a normal person - it would have stopped there. Handler. Possibly a father figure. Bitchy boss. Those were the words River and everyone around him had used, repeatedly. He supposed reluctant mentor should have been enough to explain everything.
And it did.
Except that look.
River had been winning the argument with Shirley that morning - obviously, because there was no universe in which Shirley could possibly have the upper hand over him (if he kept telling himself that, one day he might actually believe it) - when his gaze had shifted to Lamb. And what he’d seen had frozen him on the spot, his heart jumping into his throat, a gasp almost escaping him for reasons he couldn’t immediately explain.
But what had he seen, exactly?
River had no idea. Or rather, he did have an idea, but it was so far-fetched, so absurd, that his mind had flatly refused to accept it at first. Yet no matter how hard he tried to frame it differently in the days that followed, he kept coming back to the same place. It wasn’t a conclusion that lived neatly in his head; it resonated lower, visceral, twisting in his gut, setting off uneasy flips in his stomach… and something else too. A flutter of sensation further south that he didn’t quite dare name.
After that, River had done what he always did when faced with uncertainty and a dangerous situation: he’d thrown himself into it, searching for any scrap of evidence that might justify the interpretation his entire body insisted was the right one.
River was good at that, no matter what the Park thought. Following Taverner without her noticing hadn’t been a matter of luck or coincidence. When he wanted to, he could slip perfectly into the role of the silent observer, quietly and methodically reconstructing the clues. Where he usually failed was in the final conclusion, not in the gathering.
And so he began watching Lamb more closely, cataloguing every glance, every inflection, every fleeting moment. What he should have been looking for were signs that contradicted his theory. Instead, he found himself focusing on anything that might support it, searching for reassurance that he hadn’t invented the whole thing, that he had, in fact, seen something real. A self-fulfilling prophecy, some might have said, because the truth was that River wanted that to be the explanation. Maybe a little too much, and for reasons he had no interest in psychoanalysing right now.
But whatever had been in Lamb’s eyes that morning seemed to have vanished entirely in the days that followed, smothered beneath routine cruelty and habitual detachment, to the point where River sometimes wondered if he’d dreamed it, or if he’d projected something he hadn’t even been fully conscious of himself. That thought angered him, and he couldn’t escape the awareness that all of this revealed far more about River than about Lamb himself.
Still, he kept watching, waiting for signs, convinced through the same arrogance Lamb so loved to despise that he could do so discreetly, invisibly. Which might even have been true, if not for the fact that Lamb didn’t just have decades more experience under his belt.
His train of thought dissolved at the sound of Lamb’s voice.
“Finally reached a conclusion, then, Cartwright?” Lamb said at last, casual as ever, watching River from behind his desk, boots propped up on its edge, hands folded loosely in his lap.
By now, River wasn’t even surprised that the man had gone straight to the point and that he knew exactly why River was standing there now, in open defiance of self-respect and self-preservation alike. He was clearly far too aware of how much time River had spent circling the question over the past two weeks, trying to decode that look, that moment.
And yet, if River was standing here now, in front of Lamb, it wasn’t because he’d found an answer. It was because he couldn’t stand waiting for one any longer. His love for complicating things and his destructive tendencies had won once again, and River was uncomfortably aware of how close he was to begging Lamb to give him a response.
“I’m talking to you, boy.”
Lamb’s voice dragged him back into the present, and a shiver of that something ran down River’s spine, sharp enough to leave goosebumps in its wake. He lifted his gaze and met his boss’s eyes.
For a moment, Lamb held his stare. Then he scoffed softly, as if bored, and pushed himself up from the chair. River watched him move as Lamb stood, pulled out a cigarette, and lit it while stepping around the desk. He leaned back against it, one hand braced on the wood, the other lifting the cigarette slowly to his mouth as he took a long drag.
“Well,” he said eventually, a faint smirk tugging at his mouth, “if you’re here because you think you’ve cracked some great mystery, I’ve got some bad news for you.” He exhaled smoke to the side. “You’re terrible at this sort of thing. If there were answers to be found, Cartwright, I can tell you - you wouldn’t be the one finding them.”
The words hit exactly where they were meant to.
River felt heat flare under his skin, fast and ugly. His hands curled into fists at his sides before he could stop himself. Part of him wanted to wipe that smirk off Lamb’s face, to shove him back against the desk and make him stop talking. Another part, more confusing and far more dangerous, was trying to push River to do something else entirely.
“Honestly,” Lamb went on, voice lazy, dismissive, “if you spent half as much time doing your job as you do staring at people like a kicked puppy, you might actually get somewhere. God knows the Park always needs loyal little soldiers, tails wagging as they wait for their rewards.”
River’s jaw clenched hard enough to ache. His pulse was pounding in his ears now, drowning out everything except Lamb’s voice and the furious, wordless need rising with it. He hated this, hated how easily Lamb could push him, how every sentence felt engineered to knock him off balance, to make him doubt himself all over again.
You know exactly what he’s doing, a part of him thought suddenly. You know this is sleight of hand meant to make you look where he wants you to look.
But you were there. His mind added. You’re not an idiot, Cartwright. You know what you saw.
Because if The Moment had truly meant nothing, if it had existed only in River’s head, Lamb wouldn’t be doing this. He wouldn’t be dancing around the issue, needling him, putting on this whole performance. He would have looked genuinely confused, or at most mildly curious about why River had been watching him so closely for two weeks, and about River’s sudden, compulsive fixation.
But Lamb wasn’t confused. He knew exactly what they were talking about, and that alone meant Lamb was aware that The Moment hadn’t been imagined.
Focus, he told himself. Just look.
So River stopped listening to sensations and words alike and started truly looking. That was when he saw it.
Lamb’s left hand was gripping the edge of the desk. Not casually resting there, but gripping it, fingers curled too tight, knuckles pale against the worn wood. The hand stayed there even as Lamb shifted, even as he kept talking, as if he needed the pressure to keep himself anchored.
River hid his sharp intake of breath. Because in that moment, he knew exactly what that subtle gesture was hiding: it wasn’t indifference, nor was it the boredom Lamb was selling so well. It was an attempt to maintain control - control that, River was certain now, was very clearly slipping out of Lamb’s grasp.
The realisation hit him all at once, dizzying in its clarity. Lamb wasn’t brushing him off because he didn’t care, or because he found River’s behaviour faintly amusing and ultimately not worth his time. No, he was doing it because he needed to distract River from the fact that River had hit the mark exactly.
What River had seen, what he had understood, wasn’t the product of an overworked imagination or desires buried so deep even he hadn’t recognised them at first. It was proof that the reason Lamb had looked at him that way wasn’t any different from the reason River had spent two weeks trying to make sense of it: Lamb wanted River just as much as River had discovered he wanted him - and that whole situation had knocked Lamb just as far off balance as it had River.
You’re trying to scare me off. The certainty settled in River as he stared at Lamb, something close to defiance rising in his chest.
Lamb should have known better. River wasn’t easy to scare off. He’d built his entire life, his failed career, his constant brush with disaster on the simple fact that he didn’t stop when people wanted him to, that he kept going even when it was obvious it would hurt him.
And with that thought, the anger drained out of him, replaced by an unfamiliar steadiness, a sense of resolve settling into his bones, a kind of calm River rarely felt.
Something in his face must have given it away, because Lamb suddenly fell silent. His expression shifted, just slightly, his gaze fixed on River now, abruptly wary, and then - slowly, unmistakably - understanding.
River took a step forward. Lamb’s hand tightened on the desk.
“Don’t,” he said suddenly, voice low, his tone entirely different now.
“Don’t do… what, exactly, Lamb?” River shot back.
Another step.
“It seems you know bloody well what I’m talking about, Cartwright.”
Another step.
“It seems you do too, Lamb.”
Lamb’s jaw clenched, contempt in his eyes mixed with something River couldn’t quite identify. “Always so fucking sure of yourself for all the wrong reasons.”
Another step.
“Fuck off,” Lamb snapped, dangerous, his posture stiffening, “before this turns into a mess not even you can walk back from.”
“Well,” River replied, almost gently, “I’m not the one who started this.”
Lamb looked away then, just for a second, eyes squeezing shut as if in frustration, or maybe in an effort to regain some measure of control. River wasn’t sure. But when Lamb looked back at him, he realised he’d been wrong. There was definitely something there that hadn’t been before, and it looked dangerously close to guilt.
That, more than anything else, stopped River in his tracks.
“Cartwright… River,” Lamb began, his voice guarded now, stripped of its earlier bite. “This is fucked up, and you know it as well as I do.” He shook his head, running a hand over his face, as if trying to scrub the moment away. “I’m your boss. I could be your father -” he laughed bitterly, “and for God’s sake, maybe I shouldn’t have mentioned that, considering all the fucking daddy issues you’re walking around with.”
He looked at River then, a brief flicker of irony back in his eyes. It vanished almost immediately.
“This isn’t going to solve anything,” Lamb went on. “It’s not going to give you the answers or the acceptance you think you need. It’s just going to fuck with your head and with mine. In this bloody work we do, that’s far more dangerous than you realise.”
And of all the sensible, infuriatingly grounded things Lamb had just said - things River should have listened to, given how rare it was for Lamb to offer anything like this - his mind snagged on a single point.
“With my head… and with yours?” River asked softly, hope colouring his words.
Lamb looked momentarily confused. Then understanding dawned. “Oh, for Christ’s sake-” He shifted, as if to move away.
River was faster.
Two steps, and he was right there, effectively boxing Lamb in against the desk, his hand landing right next to the one Lamb still had braced on the wood. Given Lamb’s reputation, and his very real, very secret skill set, it was the kind of move that could get River killed or, at the very least, seriously broken.
He didn’t care.
Lamb didn't move.
“I just want you to say it,” His gaze lingered on Lamb’s mouth before lifting to meet his eyes again. “That you want me.” He drew a steadying breath; it trembled despite his effort to control it, but his gaze didn’t waver. “Tell me that you want me.”
Lamb’s expression turned sardonic, a crooked, sarcastic half-smile carving itself into place. “River-fucking-Cartwright,” he drawled. “Sanctimonious local hero, begging for reassurance once again. I’m surprised you’re not doing it on your knees. Your grandfather would be so proud to see you like this.”
It was a last resort, River realised, and for a horrible moment, it almost worked. He felt the familiar anger surge, hot and sharp, urging him to step back, to scoff, to say fuck it and walk away.
Instead, he redirected it.
He leaned in closer, close enough to whisper directly into Lamb’s ear, close enough to feel the shiver run through him before he could hide it.
“My grandfather isn’t here,” he murmured softly. “And if you want me on my knees, Lamb, all you have to do is ask.”
Time stopped, and River could have sworn the whole London had gone silent. The only sound he could focus on was his own heart, beating so loud and so fast that he was certain Lamb could hear it too.
He moved his face back to look into Lamb’s eyes again, and Lamb himself seemed unable to look away. They stayed like that for what felt like minutes, so close River could pinpoint the exact moment when Lamb’s resolve finally, inexorably crumbled. Lamb’s eyes dropped to River’s mouth, and his hand came up to grip the hair at the base of River’s neck, pulling him in.
Before River could fully understand what was happening, Lamb’s lips were on his, stealing his breath in a kiss that was dirty, without finesse, just raw intensity that wiped every coherent thought from River’s head and tore a moan from his mouth. Lamb adjusted River’s head, his other hand sliding to the small of his back, pushing him closer between his legs, the unmistakable evidence of what the situation was already doing to him pressed clearly against River’s own growing erection.
River’s hands left the desk and went to Lamb’s face as his tongue fought Lamb’s for dominance, breaths erratic, his whole body on fire. Then he slid one hand to Lamb’s chest and down, on his hip, pulling their bodies even closer. He was kissing Lamb back like his whole life depended on it, grinding their groins together in a way that should have embarrassed him if he hadn’t wanted it so badly.
Lamb broke the kiss for a moment, his hand leaving River’s back to move to his trousers, opening them with a dexterity that would have surprised River if his brain had been working at all. Their lips stayed a breath apart, breaths mingling, Lamb’s eyes never leaving his - steady, intent - driving him mad with desire, River's please barely there but deafening in his own mind.
Lamb started moving his hand on him, and River cursed out loud, eyes falling shut as he blindly searched for Lamb’s mouth again. This kiss grew even messier, unfocused, and it took River a shamefully short amount of time and a well-placed press of Lamb’s thumb against the head of his cock to come over the older man, a groan tearing from his mouth, his fingers digging painfully into Lamb’s hip.
They stayed like that for a moment that stretched longer than it should have, foreheads pressed together, neither of them quite ready to pull away. River tried to gather enough presence of mind to return the favour, but Lamb’s fingers closed around his wrist, tightening delicately, a small shake of his head stopping him.
When Lamb spoke, his voice was slightly hoarse, and despite the words, that alone was enough to send a jolt through River’s already spent cock.
“This,” Lamb said quietly, “doesn’t happen again.”
The words landed heavier than any shout could have.
River felt it then: the precise moment where something tipped and locked into place. Whatever had driven Lamb to that, whatever weakness had cracked open just long enough to let River through, was already being sealed away, contained, assessed. Damage control.
And still, Lamb didn’t step back, and neither did River. They stayed there, unmoving, the space between them charged and irrevocably altered. River’s heart was still racing, his body lagging behind his brain, but his awareness had caught up now, and with it came the full, dizzying weight of what they’d just done.
“We don’t talk about it,” Lamb continued. “We don’t revisit it. And you don’t come looking for more.”
River swallowed, his mouth dry, his fingers still pressing against Lamb’s hip. Everything in his head scattered, but one thing cut through the noise with startling clarity: Lamb wasn’t saying I don’t want this. He was saying we can’t do it.
“You kissed me,” River said, moving away just enough to look the other man in the eyes.
Lamb’s gaze dropped to his mouth, a flicker of uncertainty crossing his face - something River noticed and quietly catalogued for future reference. Then Lamb’s lips pressed into a thin line.
“Yes. And now I’m telling you,” Lamb said, his voice low and final, “that it ends here.”
River took a step back then, giving himself the space to really take Lamb in. The older man’s hair was more dishevelled than usual, his clothes no better, a streak of something River didn’t want to think too long about staining the front of his shirt - proof, if River needed it, of what had just happened. But it was his eyes that struck River: too blue, too bright, the barest hint of something exposed beneath the usual layers of contempt and control.
God, River thought, I was just kissing him.
And immediately after: I want to do it again. Let me do it again.
River knew, in that moment, that as much as he wanted to follow orders and be a good little soldier, as Lamb had called him earlier, this was one order not even Lamb could enforce. Because now that the gates were open, River wasn’t sure he could go back to what there had been before. And from the look on Lamb’s face, Lamb knew it too.
“Sure,” River said anyway, nodding slightly, almost amused, enjoying the way Lamb’s eyes swept over him, a brief look that lingered a second too long as River tucked himself away again.
Lamb turned away suddenly, a quiet “fuck” slipping out as he did. River watched him cross the room, grab the bottle from a shelf, and pour himself a generous glass of cheap whisky.
“Get out, Cartwright.”
Only then did River move, heading for the door without looking back. It was only when he reached the threshold, his hand on the handle, that he stopped. He lifted his gaze to Lamb one last time, watching him drain the glass in a single swallow.
“This is something you don’t get to decide for me, you know?” he said, taking a quiet satisfaction in the way the words disrupted the other man’s careful posture and left him still, his fingers squeezing the glass a bit too strongly.
Then he turned and left the office, pulling the door shut behind him.