Author's Notes: This is a Soulmate AU based on a prompt that was really fit for a fix it, so I decided to do it. It was rather quickly written, so I do hope you enjoy it and, of course, feel free to let me know what you think!

The system was quite simple – always had been, since it had appeared along with humanity itself – even if it had never particularly agreed with Torchwood. Ianto had been taught to understand it before he had been old enough to be able to read about it, and he knew it inside and out, just like anyone else. When your soulmate died, they stayed by your side so only you could see them, and waited for you until you could be reborn together – with new memories, new personalities, and ready to meet again. Until then, they would protect you from harm.

Ianto had grown up dreaming of meeting his soulmate. He'd imagined it in a thousand different scenarios, speculated – mostly with himself – what he or she would look like. He'd thought he'd been ready.

Nothing had prepared him for meeting Jack Harkness.

The next two years had been as good as they could get. It was nothing like he had imagined, it was better, and even when the world was falling apart around them, they'd managed to get through it together. There had been the occasional discussion of how the system would work for them, what with Jack being immortal, but they'd mostly preferred to live in the moment. After all, they'd always end up together, right? Ianto had always suspected that Jack knew something more on the matter, but he'd never pressed it.

Things didn't look nearly as bright as Ianto lay on the floor of Thames House, gasping for his last breath. He couldn't say that he wasn't at peace with the situation, but it was a pity, really. They'd had so much more to say to each other; so much more to do. As Jack pleaded for him to stay awake, Ianto Jones felt his eyes close for the last time.

He could feel things somehow distantly now, as if he was slowly being taken out of his body. He could hear the 456 talking and could feel the phantom touch of Jack's lips on his, and then everything disappeared, leaving him confused in the space between one world and another. He tried to call out, to find someone to help him, but there was no one.

His mind worked differently all of a sudden; he couldn't quite tell what had happened just minutes ago and how he'd found himself here. Wherever he was, it seemed that time didn't exist past the land of the living, and at some point Ianto found himself in a vast hall filled with body bags. Gwen was standing right next to him and he smiled. Finally something familiar.

"Gwen, what happened?" There was no reaction. "I think there was an – attack? Where are we?" Still nothing, and Ianto placed himself in her immediate field of vision. "Gwen! What's wrong?"

"She can't hear you," a new voice said and Ianto turned around sharply to face Jack. Gwen had yet to react to his voice as well, so that had to mean... Jack seemed to follow that train of thought because he nodded. "And no, she can't hear me either."

Ianto frowned and strained his memory, trying to remember what had happened, his eyes widening when he came to it. "Oh my god."

"Pretty much," Jack said with a small, sad smile. "But don't worry. You'll be gone soon enough."

Well, that much was clear. Jack would come to the land of the living, and Ianto would have to wait. How long, neither of them knew, but he was willing to do it. He didn't have much of a choice anyway.

Except... as Ianto braced himself for whatever was coming, he felt new, unfamiliar memories start slipping into his head. Memories of places and worlds he had never seen, but always in the same body and always, always, Jack was there. He hadn't always been called Ianto – there had been a lot of names before – Parker, Raphael, Greg, Walton, Eris (in a particularly memorable lifetime on the edges of the Andromeda galaxy) – but Jack had always been there, always the same, and always losing him.

It felt foreign and familiar at the same time, as if Ianto's mind was torn between deciding that this was the strangest thing that had ever happened to him and a more rational part reminding him that he'd felt that way before. He could remember a thousand different rememberings and all of them had ended like this – with an 'I have been here before', which usually came right before Jack died again outside of the timelessness of this world and Ianto was plunged into his new life, bereft of all the memories of his current life as he raced towards his next birth.

Ianto looked up to see Jack's face stained with tears. "I'm sorry," he whispered. "I didn't know how to tell you."

"That I've been – what? Reborn? – hundreds of times already? You just decided you could keep quiet about that?"

"No, it was just– I've lost you so often, Ianto. I couldn't bear to talk about it. But, if it helps in any way, I'm here this time. I'll help you through it."

Jack looked so desperate to help that Ianto didn't really have the heart to tell him that nothing would change regardless of his presence. Not that he could be certain of it – he'd always died alone until now – but it was better to feed the false hope than destroy it. They had so little time left.

"I wish I could return the favour," he whispered instead, "and say that I'll never forget you, but I don't think I get to choose."

"What does it feel like?" There was longing in Jack's voice. "Being reborn."

"It feels–" Ianto took a deep breath. "It feels like being burnt from the inside out. Everything you are dies and you can feel yourself changing and remaining exactly the same at the same time. In the matter of seconds, you can't remember who you were before. A few more, and you're alive again. In fact, you died with me now, so I'd say it's already starting."

"Does it hurt?"

There was no point in lying. "Oh, it does. But it's worth it." The fear was so clearly written all over Jack's face that Ianto smiled and reached up to stroke his face. The Captain leant into the caress. "You have to go now, Jack. You've still got work to do. Don't cry, now," he continued gently when a tear made its way down his lover's cheek. "I'll find you. I always do."

"It took you sixty years last time." Jack's voice broke halfway through the sentence. "God knows how long it will be now."

"We'll meet again," Ianto assured. "And maybe, just maybe, it'll be in a better world where all the alien threats aren't threats anymore and we'd be free to do whatever we like. You've always told me that you wanted me to see the stars up close, haven't you?"

Jack's laugh was tear-stained but sincere and Ianto brought him closer. "I'll find you," he repeated, looking at him dead in the eye. "You just wait."

He welcomed the kiss when it came but wasn't prepared for how it would feel. It was nothing like anything they'd shared before and he could feel it scorching him from the inside slowly until he was gasping against Jack's lips. He was determined on hanging on until the last second and the last bit of memory, as hard as it would be, but it didn't seem to be necessary. The feeling inside him wasn't the unfamiliarly-familiar one from before; it was brand new and he was suddenly separated from Jack as he gained awareness of time and space once more, thrown back into his body and into the light.

o.O.o

Waking up with someone's scream and then being tackled back to the ground into a hug, Ianto thought, was rather good compared to losing the memories of this life forever.

"You're alive! Oh, my god, Ianto, what happened?" If he hadn't already guessed by the hair in his face that Gwen was the one doing the hugging, Ianto would have realised it from the pitch of her voice.

"I think–" He opened his eyes to look around himself. Jack was still lifeless next to him and he grimaced. "I think there was a glitch in the system. Jack died at the same time with me this time, and there was something– Gwen, there's something wrong here–"

"No, there isn't." Her cheeks were wet and her eyes were red and Ianto awkwardly tried to return her hug from where he was sitting. "How can anything be wrong when you're okay? Wait." Her eyes widened even more than usual. "Does that mean that you're immortal too?"

"No idea." Ianto accepted the hand she offered him and stood up. "Jack will freak out."

"I think it'll be a good freak out, mind you," Gwen put in. "You've broken the system, right? If he dies with you, you come back?"

Ianto shrugged helplessly. Gwen had, strangely, been about as emotionally involved in his soulmate problem as him and Jack, and he wanted to give her hope, but he had no way of being sure. "Doesn't matter now," he said, kneeling next to Jack and pulling him against himself like he always did. He had work to do.