Hey guys, sorry for taking so long to update but for some reason I have really struggled with this chapter and wasn't happy with what I wrote. I have re-written this a grand total of 6 times and to be honest got really disheartened with it so walked away for a little while. Well I'm back and feel guilty as hell for making you think I'd deserted you all so again, I'm really, really sorry.

Also, please note that for most of the story, when I refer to John, it's John in Rodney's body and when I refer to Rodney it's Rodney in John's body.

A warm hand rested gently on Carson's shoulder bringing him out of his thoughts. He was struggling to sleep, anxious and bone tired which wasn't helped much by the fact that despite being comforted by his friends, he couldn't hold the only person he ever wanted to be with.

Sighing deeply to try to relive the tightness in his chest, he realised at that very moment that everything he had tried to keep inside was threatening to spill out. Raising his head, he turned his face to the side to see Teyla looking down at him, her concern evident in the frown she now wore.

'Teyla, lass m'fine. It's just....'

Teyla never found out what it was and silently gathered up her exhausted friend in a tight embrace. The tears that had threatened to come were now flowing freely down Carson's face leaving wet shimmery trails down the haggard face of her friend.

She held tight as the sobs took hold fully, his body convulsing with every harsh intake of breath as he tried to gain control. Teyla held on until she felt the sobs slowly subside and released her loving embrace, kneeling in front of Carson with one hand resting on his knee and the other gently brushing away the tears.

'Carson, you need to sleep. You will not help Rodney this way'

Carson nodded as he regained his composure, his hand resting on top of Teyla as he looked into the soft brown eyes.

'Aye, I know. I just don't know how to be strong at the moment love. It's been three days now and were no bloody nearer to figuring this out. We've had to postpone the wedding and I can't even comfort the man I love'

As the last word was whispered, his breath caught in his throat, hitching sharply as the tears threatened to flow again.

'Carson, Come, I'm taking you home'

He allowed Teyla to pull him out of the chair and felt her small hand nudge him gently towards the door into the main infirmary.

Three days earlier...........

'Incoming wormhole, it's Lieutenant Commander's Shepperd's IDC'

'Drop the shields'

Elizabeth walked towards the balcony, both hands resting on the railing waiting for SGA1 to step through. She knew they weren't due back yet but wasn't concerned seeing as Rodney had made the point of telling her he wasn't sure how long it would take and it was possible they would be back early.

'Elizabeth, I think we may need a med team the gate room'

Rodney's voice crackled through the gate room and Elizabeth frowned as she recognized the voice but the not the inflections, she made the call and waited, the concern building at the possibility of her friends being injured again.

She didn't have to wait long and a moment later the team were walking through the gate, Rodney's face was set hard as stone as John spoke to him, only she noticed that when John spoke, he moved his hands around just like Rodney did. She started to make her way down to meet them and stood on the steps listening to the argument the two men were having.

'Oh this is just wonderful Shepperd, I'm getting married in 4 days and I can't get married like this'

'What the hell's wrong with looking like that McKay and while we're at it, what the hell am I supposed to do with this?'

Elizabeth watched with confusion as Rodney pointed to his body and moved his hands up and down. Elizabeth watched as John spluttered, his face gradually turning an unhealthy shade of crimson.

'Gentlemen, this is not the place to be arguing. Would you both like to enlighten me as to what's going on and why I have a med team here?'

Both men turned and looked at her, Johns face scowling with his lips set firmly in a line. Rodney looked surprisingly........amused.

'Hey Liz, well you see there was this machine that McKay was working on and to cut a long story short there was a bright light and next thing you know I'm the proud owner of his unfit body'

Rodney (or John), Elizabeth was confused and looked at John in hope of a better explanation.

'Oh well that clarified everything didn't it Lieutenant. Elizabeth the nub of it is this machine somehow managed to switch our consciousnesses. I'm Rodney.......'

John's hands waved in front of his body

'And he's John. We need to fix this NOW and where the hell is Carson'

'Oh dear lord' Carson had heard John..........Rodney's diatribe and stood next to the gurney looking decidedly green

'Shit, Carson are you OK. I'm sorry, I didn't mean for it ............'

Rodney was cut short by the sound of the thud as Carson's knees gave way and he slumped to the floor.

Present day

Carson hadn't realised just how tired he was and collapsed into the bed. Teyla covered him with a blanket and stroked his hair back until her friend finally let sleep claim him, the exhaustion finally becoming too much for his body to bear.

She turned at the whoosh of the door to see Rodney standing there.

'Teyla, what are you doin..............Oh my god Carson, is he OK?'

Rodney walked over to the bed and scrutinised his fiancé. He frowned as he took in the too pale face and the red puffy skin that surrounded Carson's eyes. The dark bruises that had become horribly evident were highlighted by the pale skin.

'He is tired and upset Jo...Rodney but he will be well. Maybe you should try to talk to him'

'He finds it uncomfortable, and to be honest I don't blame him. It's not easy for him to look at me this way and he said he felt like he was cheating in a way. I miss him so much Teyla'

A lone tear weaved its way down towards Rodney's chin and quivered slightly before dripping off onto the Rodney's uniform Jacket.

'All I want at the moment is to be able to hold him, to comfort him but it's not the same for him. We've had to postpone the wedding you know, god I was looking forward to finally being his husband. We even decided to hyphenate our names to McKay-Beckett'

He was whispering gently so as not to disturb his lover but the pain was clearly evident as he spoke. Teyla could see the battle within him as his hand hovered over Carson's hair line but was pulled back before he could touch.

'Rodney, come here' Teyla grabbed his hand and pulled it towards Carson's head and firmly pushed it down so it was palm down resting across his lover hairline. Rodney automatically started to run his fingers through the dark hair and sighed.

'You know, I really do want to be with him. I can't sleep without him being there and moving back into my old room...........God Teyla I'm so damn lonely'

He hadn't realised how much he took for granted that his lover would be there at night, the warm body wrapping itself around him radiating enough heat to keep him toasty and snug through the winter nights. For three nights now, he had slept alone. Well not exactly slept, more gone to bed and lay awake all night.

Teyla could hear the distress and looked over at Rodney, watching as another tear ran down his face and teetered at his chin.

'Rodney, how close are you to fixing the machine?'

She knew they were having issues with the machine, Rodney had been returning to the planet on a daily basis to repair the damage done after the first transfer and the last news she heard was that the science teams were making good progress.

'Oh, um, It's going well but it's going to take a few more days, that's if the repairs work at all'

Teyla nodded and wrapped her warm arm around his shoulders. She was about to reply when Carson stirred and turned his head towards the hand stroking his hair making Rodney pull his hand back as if it had been burned.

'I've got to go, he can't see me here'

'Rodney wait'

Teyla tried to call him back, startling Carson from his slumber. He jerked upwards and found himself encased in Teyla's arms.

'Shh Carson it's Ok. Please go back to sleep'

Carson melted into the embrace and let himself be laid down, it wasn't long before he fell back into a deep slumber.

Rodney walked through the halls of Atlantis, not knowing what to do with himself. He was deep in thought and didn't see John walking towards him.

'Hey, what ya doin?

John's hands were shoved in his pockets, his head cocked as he waited for a reply.

'Nothing Shepperd. I take it you've eaten lunch; I don't want my body falling into a Hypoglycaemic coma before I get it back'.

He hadn't meant to snap but the pain of seeing Carson so frail and exhausted had upset him, the fact that he couldn't comfort him made it worse, the pain now manifesting itself physically.

'Oh crap, I was on my way to find you to make sure you eat, old habits I guess. Why the hell are you tensing that way, don't put my back out McKay'

'Ha Ha very funny. Come on we should probably go eat seeing as you'll start shaking soon'

John huffed out a laugh before realising just how serious Rodney was. He hadn't given his friends health issues a second thought.

'Yeah Ok, come on'.

They walked to the mess in near silence, Rodney only speaking when pushed. It wasn't like him and John was getting worried but knew better than to question him. Rodney would talk when he was ready.

'So, when are we due back on the planet'

John had taken to going along with Rodney, at this stage just to provide moral support or, he hoped, to turn the machine on. As much as he loved his friend, he hated the thought of being stuck in his body. It was starting to wear him down, Rodney was a lot more unfit than he was and every time he saw Carson the pain in the Doctors eyes damn near broke his heart.

'Oh, um in about an hour. I think we're nearly there so we should be able to test it soon'

John nodded and the entered the mess hall, joining the queue to grab lunch. Rodney was too wrapped up in his thoughts, force of habit made him choose the meal he knew didn't have citrus in it which was some kind of stew with whatever the meat of the moment was and root vegetables. John picked the chicken and vanilla mousse.

'So, you spoken to Carson yet?'

John saw his friend's face darken further as he started to slip further into himself. He wouldn't have minded Rodney staying with Carson, all he asked was that their sexual activities be kept to a minimum whilst babysitting his body.

'No, its........complicated. you know what John, I really don't want to talk about this right now'.

John watched as Rodney dropped his spoon and ran his hand over his face. There was nothing he could do to placate the pair. He shrugged and dug into his meal.

It wasn't long before John started to feel ill; it was sudden and took him by surprise. He could feel his tongue and airways slowly swelling closed leaving him gasping for air. Rodney looked up at the first wheeze, his eyes widening at the sight of hives bubbling up over Johns exposed skin.

'John, oh my god.......didn't you check for citrus?'

Rodney was frantically patting down john's uniform trying to find the epi pen that he should have on him at all times. The truth be known, he had always been safe on Atlantis so had stopped carrying them in the city.

'well that's gonna change' he thought as he panicked and barked commands to the infirmary.

He even checked the small pocket in his jacket that Carson had sewn in, he had gotten fed up of Rodney searching through his pockets for stuff and decided something as important as that merited its own special place.

'What the fu......John where's the pen. JOHN FOCUS GOD DAMN IT........WHERE IS THE PEN?'

Johns eyes went wide, he couldn't respond, his airways so damn tight that he was slowly be suffocated by his own body, well his own borrowed body.

He hadn't even heard Rodney's frantic call to the infirmary and didn't know someone had called for a med team until he heard the wheels squeaking through the mess, the noise barely breaking through the grey haze that was descending rapidly, threatening to pull him down into oblivion. He didn't feel the sharp prick of the needle in his thigh and felt the tightness loosening slowly, his throat gradually letting in the much needed oxygen.

Despite the epinephrine and the oxygen, John still found it hard to breathe, the raspy wheezing signalling the need for antihistamines and steroids to counteract the reaction. He vaguely remembered Rodney complaining about being biphasic and tried to tell the medics.

He felt himself being lifted onto a gurney before an oxygen mask was placed over his face. He didn't remember much more as the darkness crept in, the exhaustion taking hold making him pass out.

when John woke up later, the first thing he noticed were the all to familiar sounds of the infirmary, he felt as though his head had been stuffed with cotton wool and his tongue felt like it was ten times thicker. He felt the trickle of air tickling his nose and realised he had an oxygen mask secured over his face, he gradually started to come round more, becoming more and more aware of the steady beeping of the monitors. It wasn't those that woke him up though, it was the angry voice that rang through the infirmary.

'I'm working on it Ok Carson, what the hell do you want from me. Jesus, can you get your mind off your sheep for five minutes and listen to me. I AM TRYING TO FIX THIS'

John heard a loud sigh, it wasn't one of exasperation, it was an angry sigh that let everyone in the infirmary know how utterly pissed off they were.

'Oh for the love of god Rodney, you think this is easy for me. I can't even hug you for fear of pissing off the colonel and my guilt of you thinking I'm cheating. Aye, we do need to get this fixed before our relationship is marred beyond being sorted'

'What, Carson no, you don't mean that. Please tell me you don't mean that. Oh ..........oh.......Can't breath......hel.......'

The sentence was cut short by what John recognised as a Gaelic swear word and he lifted his head to see Rodney being led to one of the beds, his head being pushed firmly between his legs to try to halt the panic attack before it took complete hold.

'Ok love, that's it. Deep breaths. Rodney you need to calm down for me. That's it lad, that's it'

Rodney's breathing started to regulate back to normal, the panic subsiding leaving a barrage of tears in its wake. John watched as Carson wrapped his strong arms round Rodney, gently rocking him back and forth offering him the comfort he so desperately needed.

John felt as though his heart was breaking, it wasn't often he heard Rodney sob like this and wanted nothing more than to go and comfort his friend. Watching carefully his mind started to formulate a plan, they needed each other desperately and if that's what they needed then that will be just what they get. He decided to play the martyr for the sake of his friend's relationship.

Rodney pulled away from Carson so suddenly, the doctor lurched forward slightly. He was still sobbing hard, the tears flowing freely down his face. Carson's brow knitted into a deep frown and John could see the very moment his resolve dissipated.

'Oh Rodney, what are we t'do eh? Come here love'

John watched his body being pulled into a firm hug and discovered it didn't really bother him too much, huh strange, maybe it was because he knew Rodney was at the controls...........Crap, the realisation hit him like a brick. Rodney had his super gene and it would have to be Rodney who turned the machine on when the time came.

'Rodney. Come here'

John called out and startled the lovers apart, if anything he found the looks on their faces more than amusing and laughed into the mask as the pair of them looked like deers caught in the headlights.

'Oh welcome back Colonel. Now I know for sure you aren't going to kill me, I'm going back to the planet to figure out how to switch us back'

Rodney had stalked over to him, his face red with the effort of crying, his eyes puffy and moist.

'Hey sorry, I forgot Ok. I'm fine by the way, thanks for asking'

Rodney huffed and turned to walk away. John seized the moment and grabbed the back of his jacket pulling him back towards him.

'Nope, you're taking Carson home and giving him a night to remember, you both need it'

'John how in the hell is that going to happen, he feels guilty whenever I speak to him. Anyway I'm needed on the pla......'

One of John's eyebrows shot up into his hairline, he was starting to wonder whether Rodney's mind was affected during the switch.

'Don't be thick McKay, you have scientists for that. Listen, take Carson home, talk to him and become.......how can I say this......More dominant in the relationship'.

Rodney started choking on nothing at these words, the coughing soon being replaced by raucous laughter.

'And how in the world do you expect me to do that Shepperd, seriously you are delusional'

The laughter died at the serious look on Johns face.

'Ever heard of a blindfold McKay'

He winked at his friend before pulling the oxygen mask back in place, he knew it was the only way to make them both truly happy because damn, he couldn't stand the tension anymore.

He smiled to himself at the thoughtful look on his friend's face, his grin broadening when Rodney sloped off after Carson, the two men walking out of the infirmary ten minutes later.

Carson and Rodney entered their quarters; it hadn't changed much, the only difference being the complete mess it was in. Carson was usually the neat one but the days of pining for his lover left him not really caring. They had gone there to talk but Rodney decided on immediate action and walked to the wardrobe, pulling out one of his silk ties.

Carson was caught unawares, he felt the smooth silk being pulled over his eyes and felt his lover's body move round to his front, slowly unzipping the uniform jacket.

'Rodney, what are you doing? We can't do this'

He felt Rodney's hot breath in his ear before he heard what his lover had to say, relaxing slightly as Rodney whispered to him about the permission John had given him, Carson already had an€ inkling given the wink John gave him as he left.

'Are you comfortable with this though love it's just........'

Carson was cut off by a long, deep sensual kiss. It was only the mouth that was different though, the technique that drove him wild was exactly the same. He deepened the kiss and felt himself being stripped of his jacket. Once his arms were freed he started to undo the black shirt Rodney had to wear, none of his uniforms fitted properly making him look rumpled. He ran his hands down the newly exposed chest to find the fairly hairy body underneath.

'Carson, oh my god don't stop. Lose the shirt'

Carson had been playing with the sensitive nipples beneath the shirt, tweaking and pinching them until they became hard nubs. Rodney was pleasantly surprised by exactly how sensitive John's nipples actually were, he hadn't really played with himself in the shower, feeling slightly disrespectful towards his friend so he didn't really know how large John was erect or how much he could take.

His cock hardened further with the swoosh of fabric and he watch lustily as the t shirt was thrown to the floor, leaving a half naked, blindfolded Carson Beckett standing in front him. Both men had already kicked off their shoes so Rodney tackled Carson's BDU's as he moved back in for a kiss. Once his lover trousers were firmly pushed down round his ankles, Rodney dropped to his knees, taking the rock hard length in one deep swallow before moving lazily back up, licking at the pre come that had started to leak out.

Rodney's rhythm never faltered as he popped the cap off the lube and slicked his fingers, gently massaging Carson puckered hole before pushing one finger in through the tight ring of muscle. He heard Carson groan as Rodney found his prostate, waves of pleasure shooting through every muscle in his lover's body. He felt his cock twitch uncomfortably and added another finger. Gently stretching and scissoring enough so he could add three.

He felt Carson's hips start to move, the movements becoming fast and dirty as his lover revelled in the feeling of being together, the orgasm building in the pit of his stomach.

'Rodney I'm gonna...........'

Carson came hard and fast in Rodney's mouth, his lover keeping up the steady suction as Carson's hard cock released directly into the back of his throat. Rodney swallowed everything Carson had to offer and licked him clean before removing his fingers.

Carson groaned as his knees gave way, his head dropping to Rodney's shoulder with a feeling of being utterly sated.

Rodney rubbed soothing circles on his lover's lower back, not really wanting to talk at the moment just in case John's voice completely ruined the mood. He stood up, pulling Carson with him and guided his blind lover to the bed carefully stripping off the BDU's on their way. He manoeuvred Carson onto his back and lifted both legs up to his shoulders, carefully kissing his way down from his lover's ankles to his knees before pushing his hard erection firmly inside Carson, the prep during the blow job relaxing him enough to take Rodney's thick length.

Rodney noted as he pushed in that whilst John was slightly shorter, he was a little bit thicker and hoped he wouldn't hurt his fiancé too much, the worry was soon put to rest when he heard his lovers aroused groan, spurring Rodney on as he drove completely home.

They had been apart for too long, 3 whole days without being able to touch, kiss, hug or make wild inhibited love, it was too much and Rodney set the pace hard and fast. The need to re-connect to his life partner was almost desperate as he drove them both into oblivion.

Rodney felt himself teetering on the edge and wanted nothing more than to come in unison with his lover, with that in mind he stilled his movements and reached down to grab Carson's long hard erection, pumping roughly until he heard the moans of pleasure starting to get louder and the feeling of tightness around his hard cock. Rodney started to move again, hard and fast, his movements becoming more than a little erratic as he pulled them both over the edge.

Carson came a millisecond before Rodney, the increased pressure practically pulling the come out of Rodney as he filled his lover's sweet ass. Both of them slumped with Rodney panting heavily on his lover's chest, not hearing the chirping of his headset.

'Rodney, I think that's for you love'.

Carson sounded sleepy and contented it made Rodney smile as he answered his radio.

'McKay..................yes of course it was............no.........WHAT...........I'll be right there'

He disconnected the radio and pulled out of his lover, he hadn't realised he was still buried deep inside. The movement made them both groan as the movement proved painful after the amazing sex they just had.

'Carson, we need to go, they've got the machine working so we need you to come with us while we use it'.

He pulled his debauched lover up and into the shower to wash away the smell of sex. Even though he had John's permission to use his body, he found himself not really wanting to let him know exactly what had happened.

It only took them both ten minutes to get the gate room and was met by Shel pushing an exhausted looking Shepperd, he was still on the oxygen after the secondary reaction kicked in just after his friends left the infirmary and looked decidedly peaky. The dark rimmed eyes shockingly dark against the pale skin.

'Oh that's just wonderful, I give him back his body in one piece and mine comes back looking like something from the living dead'

Shepperd huffed and flipped Rodney the finger before pulling down the oxygen mask.

'Look on the bright side McKay, I'll never tease you about your allergies again. Can we just do this'

Rodney fisted his right hand and moved it up and down, god he loved the Brits and their insults, he seriously wasn't expecting John to know the sign for wanker.

'Not nice McKay, using English insults against me! Oh and by the way, I've always openly admitted to being a wanker'.

The argument was interrupted by the gate whooshing and John started when Carson pushed the mask back on his face.

'Och, if you're gonna give me back my man in that state, then at least follow medical advice and keep the bloody mask on'

John raised his hand and found it being slapped hard

'And don't even think about flipping me the finger lad, I won't think twice about breaking out the really big needles when we get back'.

Rodney giggled at the shocked expression on John's face as they were both ushered through the gate.

Awareness came back to Rodney slowly; his eye's feeling like they had been glued shut and his mouth felt as though it was stuffed with ash. He heard the beeping of the heart monitor increase, sending out a loud signal to whichever Doctor was on staff.

'Rodney, come on love. I need to you open your eyes for me now'

He knew that voice, the smooth Scottish burr making him want to melt back into the mattress and let sleep claim him once again.

'Ach, no you don't laddie, you've been sleeping for Two days now and you're gonna come all the way up this time'

Rodney peeled his eyes open slightly, the light assaulting them after being down for the count too long. He felt Carson peel one eye back and watched as his lover dropped soothing eye drops into it. Carson did the other eye and urged Rodney to open his eyes fully.

To his surprise, whatever Carson had used stopped had taken away the gluey dry feeling and Rodney found he was able to open his eyes all the way. Carson raised the head of the bed and held a cup with a straw to his fiancés lips. Rodney drank deeply as the cool soothing water replenished the lost moisture in his mouth and throat.

'Two days? Why?'

Hi memory was somewhat fuzzy and it took him a while to remember going back to the planet to use the machine to switch John and Rodney back.

'Oh........oh oh oh, please tell me it worked'

'Aye it worked love; you are most definitely back to your old self. You were hit by the effects a wee bit harder because of the reaction your body went through before you used that bloody machine. You know Radek tested it on himself and Lorne, bloody fool was lucky it didn't backfire'

Rodney nodded as he processed what he was being told, he knew the machine needed testing and was trying to figure out a way of doing it.

'M'glad he did. Missed you. John Ok?'

Carson watched as the heavy lids started to close again and started to card his fingers through the mousy blond hair. Even though they had made love, it wasn't the same and he yearned for the day his lover came home.

'Aye love, I missed you too and John is absolutely fine. He went back on light duties this morning'

Their hand interlocked and Carson propped his hand up on his elbow, relishing the sight of his exhausted lover as the sleepy eyes opened and closed slowly.

'Oh Carson'

'Yes love'

'Can we get married now'

Carson laughed as he stood, kissing Rodney deeply.

'Aye love that we can'

Woo hoo. This chapter has proven to be the most difficult one EVER!!.

Anyway, sorry again for leaving you hanging so long and I hope you all enjoyed.