A/N: To toobeauty, EsScaper, socalrose, Village-Mystic and WickedWitchoftheSE, thank you for taking the time to leave your reviews, and thank you to everyone who has favourited or alerted this story. I'm glad you all agree that this is something monumental that has not been properly explored in the show or in fanfiction; it reassures me I've done the right thing in turning it into a series.

This chapter is an edited version of the original one-shot of the same name.

Kryptonite

"I left my body lying somewhere in the sands of time"

Ianto couldn't quite remember how he'd managed to prise Jack away from the floor, how he'd managed to calm him down, to reassure him, to explain to him as best he could without causing the heartache he feared. Jack had watched him stutter uncertainly, his eyes flickering between sincere trust and utter terror. It was as if he knew what had happened, knew about Gray and Tosh and Owen and everything that had happened, but his brain was refusing to confront and accept it.

All Ianto knew was that they had to get away from the Hub, and the weight of its grief.

When they arrived at Ianto's flat, Jack sank lifelessly onto the sofa whilst Ianto busied himself making a coffee. To be honest, he would have preferred a stiff alcoholic drink, but something told him that getting drunk tonight was not the right thing to do; not the right thing for him or for Jack. He cast a quick glance in the direction of the sofa, catching a glimpse of Jack perched uncomfortably on the battered furniture, his shoulder blades hunched to his chin and his fingers tangling in his hair.

Ianto was scared – he knew he was a master of disguising his emotions, but the tremor running through his body could only be described as pure and unadulterated terror. He could feel Jack slipping away, and he didn't know what to do; all he wanted to was to crawl into bed, away from Jack, away from the world, and pretend that nothing had ever gone wrong in his life. But there was something about the sight of Jack before him, crumpled and broken, that urged him to leave the coffee-making – which had, admittedly, been an excuse to brush away the problem – and sit beside him with some trepidation.

"Jack?" he raised his hand tentatively to rest on Jack's shoulder. His fingers trailed gently over the rumpled material of his shirt, smoothing out the creases in the vain hope that that would make a difference. Jack remained silent, his head buried in his hands, pulling so hard at his hair that Ianto could see the skin at the roots reddening. The younger man licked his lips, waiting quietly.

Finally, Jack raised his head to look at Ianto, his gaze ricocheting from his eyes to his cheekbones, unwilling or unable to meet his gaze. Ianto felt his stomach plummet at the coldness in those eyes, the weight of a thousand years tugging on the irises; it seemed as though his eyes were drowning in themselves, their famous glimmer sunk beneath the waves of pain.

"Jack…" he repeated, all too aware of the uselessness of his words. He had told himself that he could handle Jack; flirtatious Jack, bastard Jack, guilty Jack; he could deal with them all, knew how to deflect the personalities and meet them head on. But this was very different, in that it didn't seem like Jack he was dealing with. Sometime, during those millennia buried beneath the soil of Cardiff, Jack's – Jackness – had escaped into the soil. He felt a sharp pain fight in the back of his throat, stirred by a slight, irrational anger:

You went once, you will NOT go again.

Suddenly, as if he had read the words pooling in his eyes, Ianto felt Jack's hand on the back of his neck, his mouth forced onto the cold lips of his lover with a relentless urgency. Ianto closed his eyes and let Jack kiss him, allowing him to reacquaint himself with whatever it was he needed to reacquaint himself with. It had, after all, been two thousand years since Jack had last kissed him, something that it had been easy to forget amidst the grief that had suddenly descended on their lives. Ianto was surprised Jack had even been able to remember his name, let alone having any memory of the sketchy details surrounding whatever kind of connection they had forged.

Jack's kiss was clumsy, unnatural, as if he couldn't quite remember what he should be doing. Ianto felt his shoulders tense, sensing his obvious frustration and trepidation. Fearful that Jack was slipping away, he moved his hand from Jack's arm to his face, cupping his cheek and brushing a thumb gently over the jaw. Jack pulled back, an expression on his face that was impossible to read; Ianto smiled what he hoped was a reassuring smile, and leant forward to capture Jack's lips slowly in his own, hoping that Jack would trust him to take control.

Feeling little response, but also little resistance, he tentatively ran his tongue along Jack's bottom lip, questions and uncertainties thrumming in the slightly awkward movement. The bottom of his stomach lifted a little as he felt Jack's mouth open slightly, allowing his tongue to brush in and over his teeth, keeping the movement as gentle as possible until he felt Jack's own tongue responding to his guidance.

"Ianto…" Jack murmured softly against his lips, obviously testing the vowels, rolling them on his tongue like some sort of foreign language. Ianto was struck by the suddenness of this change in the man – when Jack had freed them from the cells, he had seemed no different to the Jack they had left behind. He realised that somewhere, in between Tosh's death and Ianto finding him sprawled on the floor, blood pooling from the gunshot wound in his forehead, something in Jack's mind had snapped. All those millennia alone, suffocating and reviving, the weight of six feet of earth pressing down on his lungs, had caught up with him once the immediate danger was over. The moment Jack the Hero had no longer been needed (the moment Gwen had left the Hub – she still viewed him as a heroic figure, after all), Jack the Human had taken over.

Jack the Human was broken.

"Ianto…" Jack tried again, his voice more forceful than it had been before, as if the name was the key to something fundamental in his brain. "I need…I don't remember…" He scrambled for words, obviously missing something. Ianto, knowing that he himself was not much of a talker, waited patiently, his hand still framing Jack's cheek comfortably.

"I want…I need…but I can't remember how…" Jack's voice was pitiful, vulnerable, barely more than a whisper and cracking with invisible tears. He flicked his eyes to meet Ianto's, his hand tentatively reaching up to the long fingers caressing his face and travelling along the length of his arm; the uncertainty was almost unbearable, as if Jack expected either himself or Ianto to shatter into a million pieces. The immortal man had never been one who was good at expressing himself with words, and Ianto had quickly learnt the art of deciphering Jack just through his touches. And he understood.

Gripping his wrist, he stood up and drew Jack with him. Jack complied, his limbs pliable, like jelly almost. The Welshman took a step backwards, and then another, keeping his eyes intently fixed on Jack's face.

"Tell me what you want Jack," he whispered, barely noticing as his back grazed the doorframe of his tiny bedroom. "I need you to tell me what you want me to do."

Jack's eyes flickered from Ianto's face to the bed, his eyes pleading with Ianto. He closed his eyes and breathed in, gripping Ianto's sleeve with a vice-like grip. Ianto held his breath along with Jack, hoping that he was doing the right thing – hoping that he hadn't misinterpreted what it was that Jack wanted, what Jack needed. In a selfish part of Ianto's brain, there was a slight flicker at the thought that Jack needed him…

Watching intently as Jack opened his eyes again, he began to unbutton Jack's shirt and ease it slowly from his body, letting his fingers caress as gently as he could over the newly exposed skin of his arms and shoulder blades. When Jack didn't protest, he hooked his fingers under his white – now greyish brown – undershirt and inched it up, just enough so that he could run his the pads of his fingers gently over Jack's stomach. The Captain's eyes slid closed again gently as Ianto hand wandered along the waistline of his trouser, carding through the smattering of hair that grew from his naval downwards.

Ianto took this as a good sign, ghosting his fingers over the button of his trousers, sliding it through to loosen the garment from Jack's body. He moved slightly closer, pressing his cheek against Jack's, feeling a slight swelling against his thigh as Jack's pulse grew more frenetic.

"I need to know if this is what you want, Jack".

Jack's eyes opened, his hand inching to Ianto's own waist, un-tucking Ianto's shirt from his suit trouser and mimicking the actions of the younger man.

"I need to feel," he whispered firmly into Ianto's ear. "I need to know you."

Keeping his hands as steady as he possibly could with the weight of responsibility he felt on his shoulders, Ianto stripped Jack of the rest of his clothes, letting Jack help him remove his own before leading Jack to the bed and encouraging him to lie on his side. Jack's body tensed slightly as Ianto slipped behind him, looping an arm around his waist and pulling his back flush against his chest. Jack's breathing was catching, the lack of familiarity and his inability to remember by turns frustrating and terrifying him. Ianto was used to being the one taught by Jack, the one with the least comparative experience, and now those roles were completely reversed – it was a heavy responsibility, almost like taking Jack's virginity, a thought that would have seemed absurd if the weight of it wasn't so real.

Leaning to the bedside cabinet, he scrabbled around for the tube of lubricant he and Jack had stashed away for the rare and often unplanned moments when they decided to ditch the Hub for the modesty of his flat. Finding it beneath his fingers, he warmed it in his palm, pressing his nose into Jack's hair briefly and breathing in his scent. The familiar Jack smell was still there, masked slightly by the layer of dirt, and Ianto took some comfort in the familiarity that ran through his body as Jack's pheromones seemed to set his senses on fire. But he ignored his body's natural reaction, stopping himself.

"Are you sure?"

"Will you just shut up and fuck me?"

Ianto felt a small smile quirk the side of his mouth at the glimpse of the Jack that he knew, the Jack whose seemingly-perpetual sexual frustration created an almost childish impatience when it came to the bedroom. Jack was still in there, and that thought spurred him on as he gently slid a slick finger into Jack's entrance. Jack tensed around the digit, a hiss escaping his mouth as he was breached for the first time in a hundred lifetimes. He was incredibly tight, and his discomfort was clear – he hadn't had human contact for nearly two thousand years, a thought that even Ianto, who had spent a lot of his life avoiding intimacy in all its forms, could not bare to think about more than absolutely necessary. Even with this knowledge, the frown that appeared on Jack's face almost encouraged Ianto to stop, to pull out, to just lie there and hold him as tightly as possible. It would have been simpler, but the older man reached around, gripping his wrist to keep his hand in place and grunting softly:

"Keep going…I need this".

Sliding in another finger, Ianto pressed a gentle kiss against the back of Jack's neck, inwardly apologising for the discomfort he was causing, silently promising that it would get better, that it wouldn't hurt, that he just had to wait, to relax, to let him in. Jack seemed to pick up on Ianto's subliminal message, both in its physical and emotional meanings, doing his best to relax his body, letting the muscles around Ianto's fingers go slack and dropping his head back onto Ianto's shoulder. Continuing to stretch Jack as gently as he possibly could, Ianto inched forward to ghost his lips over Jack's, letting him respond in his own time, on his own terms, smiling softly around Jack's lips as he felt an exploratory tongue force its way into his mouth.

For a moment after realising that he had prepared Jack as much as he needed to, Ianto hesitated, a thousand thoughts flitting through his already overloaded brain. The loss that they had suffered washed over him, the grief crashing in his brain; his worry for his surviving teammates; for Gwen and her destroyed belief in goodness; for Jack and his crumbling mind trapped in a indomitable body; and, alongside them, the comparatively trivial question of whether he should be considering using a condom. Just how did you judge that kind of the thing in the impossible situation he was presented with? No sex-education counsellor had ever offered advice on safe sex with an immortal man - Ianto supposed he would just have to work it out for himself, something he was well used to doing. Jack had been buried for over two thousand years, had died countless times, there was no chance that there was any danger. And, anyway, he wanted Jack to really feel him inside of him.

With this thought in mind, he quickly slicked himself up and positioned himself behind Jack, his hand steadying Jack's hips and tilting him gently to make it as comfortable angle as possible for his lover, who was now fisting the bedclothes with a trembling hand. Easing himself in, he kept his other hand entwined in Jack's hair, stroking gently through the locks in what he hoped was a reassuring, calming measure. Jack himself kept his eyes squeezed shut as Ianto pushed into him, his face tense and a bead of sweat forming on his brow as his younger lover breached his body.

The moment he was completely filling Jack, Ianto stilled in him, waiting for some sense that he should continue. Jack held his breath for what appeared to Ianto to be an eternity, clenching uncomfortably around Ianto's cock. All Ianto wanted to do at that moment was move, to feel Jack against him, to alleviate the building pressure in his groin; but he was stronger than that, he told himself, and he was in control now. He remembered how careful Jack had been with him on their first encounter, how aware he was of his injuries sustained in the countryside, and yet at the same time willing to fulfil that desperate need to be held and touched and fucked into the mattress. Now that the impossible situation had arisen, that Ianto found himself in Jack's shoes, he knew he was willing to wait for as long as it took.

Finally, Jack moved his hand to slide over the fingers at his waist, gripping tightly onto Ianto's wrist and pushing his hips back into Ianto's groin. Pressing his lips once more into the short hair behind Jack's ear, Ianto began to move his hips, sliding his cock in and out of Jack as gently as was humanly possible. Jack's fingers laced with Ianto's on his hip as his breath hitched, the frown on his forehead contracting and tightening as Ianto filled him, before changing from pain to surprise as Ianto finally hit the right spot.

Hearing the gasp of surprise escape from Jack's lips, Ianto buried his face into his lover's neck and began to pick up his pace, hooking an arm around Jack's waist to fist around his cock. His movements around Jack contrasted to his movements within Jack; he couldn't find the right rhythm, instead opting for a random mix of thrust-stroke movement that nonetheless encouraged just the right noises from Jack's lips.

He knew that any psychologist would warn against this. The notion that sex could heal wasn't one that he had ever really bought into; it hadn't been the sex that healed him following Lisa's death, following the pain and the grief and then the abominably unsuccessful team-bonding session to the country. That physical connection had helped, he had no doubt, but Ianto had had one night stands and casual fucks before. He knew that they didn't alleviate the pain - they cured the present problem, allowed him to forget for that moment, but the effects were fleeting. No, he could conclusively say that sex didn't work as therapy. But sex with Jack was different. Jack was a being stuck in a time that didn't understand him, a man who tossed aside the restrictions of labels and categories in favour of unconditional connections. He was rooted in the sensual, and every single encounter, sexual or none, was deeply intimate. Ianto had needed to be touched, to connect, to feel some sort of intimacy, and that was what Jack had offered.

Ianto wanted to give Jack exactly what Jack had given him; to remind him that, although he was lonely and isolated and broken beyond belief, he wasn't completely alone.

Jack tensed against him, reaching back to dig his nails into Ianto's thigh, his harsh, raspy breath an obvious sign that he wasn't going to last much longer. With one last thrust of his cock into Ianto's hand, Jack found his release with a resigned sigh, succumbing completely to the sheer physicality chasing away the screaming in his brain. Feeling the muscles of Jack's body relax completely for the first time that evening, Ianto propped himself up slightly on his elbow, pulling Jack towards him to lift his hips ever so slightly, eager to join Jack as quickly as possible in his completion. With a few more frantic thrusts into Jack's pliant body, he felt the tightness coiling in his stomach build and release, muffling the low groan in Jack's hair as a he was hit by a crushing wave of pleasure-pain-grief.

The sound of their breathing gradually slowing was the only sound that filled the air as they came down, Ianto reluctantly pulling out of Jack and resting his cheek against his shoulder. An incredible stillness filled the air, a relaxed aura the emanated from both the men as they lay as still and as close as possible; there was no doubt that something had been gained, something had been learned, but they were at a loss to accurately describe what that something was. As it always had between them, Ianto noted, the silence spoke louder than any shallow words could possibly have done.

Finally Ianto managed to summon enough energy to work his limbs properly, rolling out from their tangled limbs and heading to the bathroom. Emerging with a towel, he quickly cleaned them both up before sliding back into the bed, rearranging their limbs so they were more comfortable. Jack lay still with his eyes closed, hardly responding to Ianto's touch as the younger man curled around him, waiting patiently, but worriedly, for some sort of response.

Eventually the young Welshman felt calloused fingers curl around the hand that was rested on Jack's stomach. It wasn't much in the way of movement or communication, but it reassured him that Jack wasn't completely gone, that they hadn't made the wrong decision in trying to reconnect in this way.

"Ianto," the word sounded more familiar now, rolling nicely off the tongue, the vowels lilted in just the way that made Ianto feel known. But Ianto couldn't help noticing that there was something, somewhere, that was still missing.

"I think I need your help."

Thanks ever so much for sticking with me! Once again, all mistakes are mine. I'll try to update as soon as possible, but if I take too long please poke me. And, in the meantime, go and see the new pictures from the filming of Casimir Effect - it's good to see Gareth working again!