Prologue – Cardiff, July 2009

Jack Harkness twisted onto his back so he could look at the man who had been spooned around him. The light in the bedroom was dim, with only the moon and the streetlight outside the window providing any illumination, but it was bright enough for him to make out the key features of his lover's face.

His gaze swept across the high forehead, down his nose, across the planes of his cheeks. He told himself he wasn't memorising the profile, tried to convince himself that this wasn't the last time he'd ever see this sweet boy he'd come to adore.

It didn't work, so he switched tactics. So what if it was the last time, he told the voice in his head. He'd only know Ianto for a few weeks; all the things his heart was telling him couldn't be true. This wasn't love, not really. It was infatuation, nothing more. He'd have forgotten all about him in a few weeks, months at the most.

He wished he could wake him up, say goodbye, but there was just no way. How could he tell him that this was it? That they would never see each other again, but that he couldn't explain why, or where he was going?

This, he knew now, had to be part of the reason this sort of thing was forbidden.

It was right there in black and white in the mission guidelines he'd been forced to memorise before ever being sent to carry out a task.

Rule 34: Maintain only the minimum level of contact with the locals required to establish your cover. Do not

inform any of the local population of the true reason for your presence

form undue attachments to any member of the local population

give any information to any member of the local population that should not be known in that time period

He'd always assumed that the rule was just part and parcel of the overarching directive that an agent should not, whatever he or she or it did, tamper with the timelines. They were there to fix them, not to break them all over again.

He stroked a finger very gently along the arm that Ianto still had wrapped around his torso, hoping that the touch wouldn't awaken him.

He hadn't intended to break the rule – it wasn't a rule he'd ever broken before. That wasn't to say he hadn't enjoyed himself, but joyous, wild, abandoned sex wasn't really the same thing as 'forming an undue attachment', was it? And could they really expect him to resist when they sent him to the places they had?

His roommate in the training core had had a catchphrase. 'So many species, so little time.' Jack had led a relatively sheltered existence until his arrival at the Time Agency, and the phrase had stuck with him. In the three years since he had graduated as a fully qualified agent, he had set out to live his life by that maxim.

And then Ianto had happened.

On paper, this mission hadn't looked like the most exciting proposition. Simple monitoring job to make sure the timeline didn't bend so far that it broke, few weeks' work at the most. And in the 21st century, on Earth.

Most of the population hadn't even met tentacled aliens yet. Jack had just wanted to get the task over and done with as quickly as possible; in, out, onto the next thing.

He certainly hadn't been expecting that he would, in boring old 21st century Cardiff, with nothing but other humans around, completely by accident, meet the most beautiful and enchanting young man he'd ever seen in all of his twenty-two years.

He had bumped into him on the way into a coffee shop one morning – literally. Ianto had only just escaped having his coffee spilled all down the front of his shirt, the hot liquid spilling only onto the pavement instead.

Jack had apologised very offhandedly, not really looking where he was going, and then he had looked up. A pair of intense blue eyes had arrested him and he had frozen on the spot.

He had hurried to apologise more sincerely and ushered the man back into the coffee shop, assuring him he would buy him a new coffee to replace the one he had spilled.

He'd introduced himself as they waited in the queue, his voice uncharacteristically tentative. By the time they reached the front, they had started to chat lightly, and it took the barista asked them five times before they even realised that they had reached the front.

Jack had ended up very late to his monitoring station that morning. He'd never asked what Ianto had been headed to that morning, but he suspected that he might have been a bit late too.

By the time they'd left the coffee shop, Jack had been smitten.

Ianto – much to Jack's relief – had seemed to be much the same way, and a few days later had seen them wrapped up in each other almost to the exclusion of all else.

Jack had still managed to get in the hours of monitoring required to complete his mission, and the day before, the last chance there had been that the timeline would snap had passed.

His mission was over, and he knew he had to return to base. Return to 5049.

Leave Ianto.

He hoped Ianto hadn't noticed anything different the night before – he didn't want to worry him. Although he knew it would hurt Ianto for Jack to just disappear on him, he didn't want those last memories to be tainted for Ianto by night-long suspicions.

He knew he had to get up and leave, but it was so hard to do. So hard to climb out of a warm bed with a man he was utterly besotted with and travel back three thousand years into the future to a place where he'd never see him again.

He shifted over onto his side, facing Ianto, drinking him in in one long look. Watching the moonlight play across his face, down across the top of his naked chest.

He really didn't want to leave, tearing himself away was torture, but he had no choice.

Very slowly, trying to make sure that he didn't wake Ianto up in the process, he rolled away to the side.

Ianto snuffled and roused a little as Jack carefully stood up from the bed. He froze and turned back.

The sheet slipped a little further down Ianto's body, baring him almost to the waist, but he didn't wake up, instead snuggling closer into Jack's now empty pillow.

Jack backed away, picking up his clothes and slipping into them as quietly as possible. His vortex manipulator was in his pocket – just to be sure, he wouldn't put it back on until he was safely away from Ianto's little flat.

He wanted to go back, give Ianto one last kiss, a kiss to really remember him by. He didn't.

He couldn't bring himself to just leave, though.

He rummaged cautiously through the collection of detritus on Ianto's desk, locating a notepad and a ballpoint pen.

He hovered for a moment with the pen above the paper, trying to think of what he should say. What he could say.

Sorry.

Jack

He tore the page off the top of the notebook, folding it once and setting it on his empty pillow.

Leaving a note… it felt almost primeval, and it definitely wasn't something he'd normally do, but…

He picked up his jacket and strode towards the door. He paused at the threshold, turning back around for one last look. The note was visible on the pillow beside him, and Jack's heart clenched.

He dropped the coat back over the chair and, picking up the pen, returned to the side of the bed and picked up the note.

Leaning on the wall, he made a few modifications. They weren't much, but Ianto had to know, even if Jack wouldn't be around.

Sorry.

Love,

Jack

xxx

Steeling himself, he put the note back on the pillow and – not letting himself risk another last look – he swept out of the door.

Ianto shivered slightly as a slight breeze blew across his body, and screwed his eyes up against the sunlight streaming through the open curtains. He reached over to touch Jack, to curl against his warmth, and felt nothing but cool sheets.

He opened his eyes. The other half of the bed, which for the last several weeks had been occupied by Jack almost every night, was empty. He was certain it hadn't been when he'd gone to sleep the night before.

He felt the sheets again – yes, definitely cool. Jack had been up for a while.

It felt odd. Every night so far that Jack had stayed over, he had still been there in the morning, curled up around Ianto, with his chin almost invariably snuggled into the crook of Ianto's neck.

Waking up after a night together to find him gone… It hurt more than Ianto wanted to admit to himself. This was just a fling, a bit of fun while he took care of some business. It wasn't supposed to be serious.

Yes, he'd already delayed his departure by over a week because of it, but… that didn't mean anything, really.

He'd already been here for nearly two weeks when he'd first met him. Just setting things up, creating the illusion of a life here, the illusion he'd need when he went in for meetings.

He hadn't really had anywhere specific to be that morning, but had stopped off at a little coffee shop that had sprung up between the last time he'd visited Cardiff and now. Coffee in the 20th and 21st centuries was just – in general – so much richer than he'd ever managed to find anywhen else.

It had been a nice day, so he'd thought of a nice cup of coffee to take with him on a wander around the city, to see what else had changed in the intervening decade.

He hadn't, admittedly, been watching where he was going as carefully as he might have been when he exited the café, cardboard cup in hand. But he hadn't been expecting someone to come barrelling straight into him, and definitely hadn't been expecting to be barrelled into by a gorgeous chisel-jawed Adonis.

He'd only barely managed to make his body move quickly enough to avoid a shirt-full of hot coffee.

He'd looked back up and found himself staring into clear, intense blue eyes. It took him a second to recognise that this handsome stranger was urging him back into the coffee shop, offering to buy him a replacement coffee for the one he'd just tipped at his feet.

They'd introduced themselves in the queue at the counter, and before they'd even realised, it had been hours later and they were still talking. Everything had just spiralled right out of control from there.

He sat up, intending to pull on some clothes and check the rest of his flat – just in case Jack was only up reading, or – well, no, not watching television; he couldn't hear anything.

There was a crinkle on the bed next to him, and he reached out to see what it was.

It was a note – he searched his memory, trying to recall everything he'd read about the twenty-first century. Was leaving a note the done thing right now if you abandoned a lover in the morning without saying goodbye?

He opened it, read it.

Sorry.

Ianto's heart clenched. Sorry for what? Sorry for leaving that morning? Or sorry for something else, something more serious?

He got up, got dressed, and rummaged around for the clunky mobile phone he'd been using since he arrived. He pressed the button he'd designated to phone Jack – no answer.

His business having concluded a week ago, Ianto had nothing much to do the rest of the day except fritter away the time and try to contact Jack.

When, by lunchtime the next day, he had still had no luck in contacting him, he had to face the facts. Jack was gone, and he hadn't said if or when he'd ever be back.

All Ianto had was an apologetic note and a 'love, Jack'.

He told himself this was a good thing. He should have been gone himself ten days ago. He just hadn't been able to find a good way to break it off with Jack before he went. Jack had taken the problem out of his hands; he should be pleased.

Instead, all he could feel was an ache inside, and he wondered if this was what heartbreak felt like.

He didn't have the time to dwell, though. He wasn't getting any younger; he had places and times to be, and keeping busy would surely keep his mind off Jack, right?

He pulled a backpack from the cupboard and started collecting up anything from the flat he wanted to take back. Most of it could just stay – he was bound to end up back here at some point, maybe in another five or ten years, just to be safe.

It was so much easier now to maintain a flat without having to actually be there – the small number of bills that actually required paying when he wasn't there could be done automatically, unlike when he'd first bought the place in the 1970s.

He took a pile of the clothes, a few knickknacks he'd picked up that he liked, all of the paperwork regarding his business here. Packed them carefully into the backpack – it wasn't like he was in so much of a hurry that he couldn't take the time to fold his clothes and pack neatly.

And the note. He couldn't quite bring himself to leave it behind, no matter how much he tried to convince himself it would be better if he did.

His lifestyle just wasn't compatible with those sorts of attachments – especially not when they were made in the wrong century entirely. And even ignoring everything else, he was only twenty-one – he had plenty of time to test the waters before he even thought about settling down.

He tucked the note into a side pocket of his bag, replacing the vortex manipulator that had previously occupied the small space.

He opened the flap and checked a few readings – yep, the signal scrambler was still working just fine, and the Time Agency would still believe this particular manipulator had never even left the equipment warehouse, and had certainly never left the 51st century.

He took one last look around the flat. Nothing was too out of place, but it still looked believably lived-in. It would be okay for a while, until he needed to return to this century again, if he needed to return again.

He strapped the manipulator onto his wrist, and set the coordinates for the middle of the 34th century. One quick little stop to check up on a few details, transfer a few accounts, and then it would be back to 5058.

Back to his 'real' job, where no one would even suspect he'd been gone.