The day at the museum went quite well in Jack's estimation. He had finally concluded that John was definitely interested in him. It wasn't that Jack didn't like the attention -- there was actually something he privately enjoyed about seeing the Doctor's body flirting with him, even if it wasn't the man himself in control of it. It was the knowledge that there was nothing he could do about it that was frustrating. And yet, he hated seeing the Doctor's -- John's features slack in disappointment every time Jack did not respond to his subtle advances.

Well, he supposed, it wouldn't hurt to respond a little. He didn't want to hurt the man; he needed to at least be his friend. He wondered how long the Doctor had been hiding and when it would be safe for him to come out.

"How long have you been here?" he asked casually.

"Three days," replied John. "And I'm going to stay four more -- a week's holiday."

"So, you took the train over, or what?"

"Yes," said John, nodding. "From London–that's where I live. I've got a flat there. It's in a nice neighborhood, I quite like it. My favorite place I ever lived. It used to be an old house. I like old things."

"Me too," agreed Jack. So, he supposed that was a real memory -- the TARDIS was probably in London, then. "I'm here two weeks. I got here yesterday."

John nodded, as if filing this information away for later. "This is a lovely piece," he remarked, pointing at the painting they were now standing in front of. It just looked like a bunch of lines to Jack. "It's all mathematics, really," John was saying. "It's just planes and angles."

Jack's mind was racing. If the TARDIS was in London, he really did need to tell Martha what had happened. With no one to keep him near the TARDIS, he had traveled as a human. That was even more dangerous.

"It's actually quite like what I'm working on," said John. "The Greeks, you see, they knew everything. Euclid in particular."

All Jack knew of Euclid was that he had been Greek. "Like what?" he asked.

John seated himself on a bench opposite the painting. He patted the seat next to him to indicate that Jack should sit beside him.

"Euclid was brilliant," he said, as Jack sat down. "He knew of the commutative property, you know?"

"What's that?"

"It's extremely basic -- you probably learned it in primary school, even if you didn't get the name. It means that when you're doing multiplication or addition, the order doesn't matter. Any combination gets you the same outcome. Two plus nine over here makes eleven, same as nine plus two makes eleven." His knee was resting casually against Jack's. "No matter what form it's in, it's still the same."

"So, you study Euclid?"

"Oh, yes, I've written a book about him. It's fascinating how much the ancients knew. I would have liked to see him–it sounds silly I know."

"What?"

"Well," John turned to look at him, leaned in close and conspiratorially. "Sometimes I dream–totally unconsciously, mind you, just dreams–that I've gone back in time. There I am, in Pompeii or someplace." He laughed. "Isn't that funny?"

Jack grinned. "Maybe one day you'll meet Euclid. In your dreams."

"Yes, that would be nice, wouldn't it?" John stood up. "I always thought people who had recurring dreams were making them up."

Jack stood up too. "So you've dreamed this before?"

"It's only started recently." He led them toward a sculpture in the middle of the room. "See, that–that's just Platonic solids. And they call it modern art." He chuckled. "It's as old as anything."

"When did these dreams start?" Jack pressed.

John looked surprised. "Oh, I don't know." He ran a hand through his hair. "Maybe a week ago? I've been having a lot of stress. That's why I decided to take a vacation. It was last minute, this trip. Just a bit of stress-relief."

Jack nodded. Maybe that meant he'd only been in hiding for a week. He wondered what had happened to make him decide he needed a vacation so soon after arriving in this time.

"Do you want to get dinner?" he asked, hating the way his voice shook.

John grinned. "We're getting quite attached, you and me! Sure. Where do you want to go?"

John ended up selecting the restaurant, as he'd done more research–he actually had a guidebook, something Jack had neglected to get. (Or, really, Gwen had bought him one, but it was sitting unread on his desk back at the Hub.)

He led them to a small, intimate place. All the tables were booths and they were all separate from each other, giving the diners a good deal of privacy.

Jack enjoyed this night's dinner much more than the previous night's. Maybe it was because he liked Italian better than seafood, but he also felt more comfortable with John. He still knew scientifically that this was really the Doctor, but he also genuinely liked spending time with John Smith. He was clever and funny, and he seemed to like Jack too, which gave him a little thrill.

By the end of the meal, they were sitting as close together at the booth allowed. Their feet were touching under the table, and when John leaned forward to brush his knees against Jack's, he knew instantly that there was no turning back from this point. He could… he could tell the Doctor, when he came to his senses that he was just keeping an eye on him in whatever way possible. He swallowed hard. "Dessert?"

"We could split something." John pulled the dessert menu toward him. "The tiramisu looks good."

The tiramisu was good. Jack didn't exactly consider himself a dessert connoisseur, but this was delicious, though, his opinion could have had something to do with the way their hands kept brushing, or the way John kept slowly licking his fork, sliding his tongue between the tines. It was incredibly distracting, that tongue, and it tugged Jack's stomach with desire.

"Did you have any plans for later this evening?" John asked.

Jack shook his head; his mouth had gone dry.

"Good." The corners of John's mouth lifted into a small smirk. "I was wondering if you'd like to come over to mine–if you're really interested in Euclid, I could show you some things." He signaled the waiter for the bill.

Jack set down his coffee and leaned forward. "I think I'm really interested in… Euclid."

**

John kissed him in the lift, rough and desperate at first, as if he'd been daring himself to do it for a long time. Jack was lost in the taste of him–espresso and something more, something he couldn't place. Their tongues met, and then retreated, a careful dance, a gentle persuasion. They barely noticed when the lift dinged and the doors opened. John broke the kiss with a grin and nodded down the hallway. Jack followed wordlessly.

"I've got to unlock the door," John said huskily, digging through his pockets to find his room key. "Then we can… then we can go in." He found it, swiped it quickly and led the way inside.

They stood there in silence for a few moments before John said, "I'm sorry, I shouldn't have–"

"No." Jack crossed the room and pulled him close. "Don't be sorry." He swallowed hard. He knew he had passed the point of no return… maybe the Doctor would remember that he had started it, that it hadn't been Jack's fault, but then, he was kissing John, was taking off his jacket and undoing his buttons and he could no longer say that it wasn't his fault.

"Are you sure?" John asked as he pushed him down onto the bed. He was sliding Jack's T-shirt up with one hand and undoing his trousers with the other.

"Positive," Jack whispered as John trailed kisses down his stomach, heading for the place Jack wanted his attention. It was hard for him to get the image of the Doctor out of his mind–this was the Doctor, after all, even when it wasn't. Those were his hands, his lips, his tongue. If this was the wrong decision, so be it. He wanted this, and John did, too.

Over the past couple of days, it had become clear to him that John was his own person, separate from the Doctor, with his own habits, quirks and desires. John was interested in Jack and he returned those feelings. Who could fault him for that? John's tongue curled delightfully in the perfect spot, and Jack gave up on thinking at all.

**

Jack had forgotten what it was like to wake up with another person in the pale light of early morning. He remembered how much he liked the sensation of a warm body snuggled against his, and he especially liked the way John's long limbs entwined with his. He idly remembered that the Doctor wasn't supposed to be this warm.

The other man was still asleep, his head resting on Jack's chest, his hair tickling his chin. Jack shifted his arm, looping it around John, feeling the beat of the single heart in his chest. John stirred, but did not wake.

Suddenly, the enormity of what he had done hit him. What was he going to do now? When the Doctor changed back, he was going to remember Jack taking advantage of him. He closed his eyes. He had to do something.

Carefully, he extricated himself from John's embrace. John still didn't wake up. Maybe if he called Martha… where were his trousers? No, he definitely couldn't call Martha… maybe he just ought to go. He hated the idea of leaving John, didn't want him to have the experience of waking up and having Jack not be there, but maybe it was for the best. At the very least, if the Doctor remembered it, it was possible that he would not say anything if it stopped here. He carefully stepped into his trousers and went looking for his shirt.

His eyes were drawn to something glinting on the dresser. It was the fob watch. Tentatively, Jack picked it up. The Doctor wouldn't miss it, couldn't even see it. If he just held onto it until he could figure out what to do…

Jack stuck the watch in his pocket.

"Jack? What are you doing?"

Jack whirled. John was sitting up in bed, looking at him in confusion.

Jack looked down at himself, half-dressed. "I was just going to… bring you breakfast."

John smiled. "That's nice, but I'd really rather you stayed. We can get something later."

Jack pulled off his trousers again and climbed back into bed, calmly complying with John's wishes, despite the fact that his heart was racing. He knew he should have left, until he could get the situation under control, but the temptation was too much. He kissed John gently, pulling him close, and they lay there for several minutes, exchanging long, lazy kisses.

Suddenly, John pulled back and took a deep breath. "You know, this is going to sound mad."

Jack grinned, twining his fingers in John's hair. "Try me."

John smiled slowly. "I think I dreamed about you last night. You were traveling with me… back in time… far, far in the future." He paused. "The really mad thing is, I think I've been dreaming about you for a while. Is that possible?"

"I don't know," said Jack. "Do you think it is?"

John frowned. "I'm positive I dreamt about you before I met you. I swear!"

Jack nodded.

John slid closer to him and rested his head on Jack's chest. "What does that mean? Is it… is it destiny?"

Jack kissed the top of his head. "I don't know," he said honestly. "It could be coincidence."

John nodded. Finally, he said, "Is there a difference?"

Jack shrugged. "I don't know."

John looked up at him and smiled. "Then we'll find out together," he said, kissing him.

They ate from room-service that day, barely getting out of bed. Jack tried to ignore the niggling feeling of guilt in the pit of his stomach. He knew the world needed the Doctor, that he had to get him back to the TARDIS and get him his memories back. But this wonderful, brilliant man in his arms, with only one heart, was an entirely different person, and it wasn't fair to make John Smith give up his life so that the Doctor could exist. Was it?

**

Jack and John spent the next few days together. They found different museums to go to and they even spent some time on the beach. Jack savored the time he spent with John, whether they were browsing art galleries, wading in the surf or lying in bed. By the end of the week, Jack didn't want it to end.

One evening, the evening before John was to return to London, they were sitting on the balcony outside Jack's room, looking out at the sun setting over the ocean.

"Jack?" said John, breaking the peaceful silence.

"Hm?" Jack lifted his head from John's shoulder.

"I think I must be going mad–I've been thinking that rather a lot lately, but I'd really like to ask you something."

"Shoot."

"Come with me. Back to London."

Jack sat bolt upright. "You want me to come with you?"

"Only if you want to." John looked away. "I remember you said you had another week or so before you're expected back in Cardiff. I want to spend it with you, but I have to go back."

Jack looked at him open-mouthed.

"And you said you weren't sure what to do next, which made me wonder if… eventually… you might be interested in… well. Only if you want to, that is. I mean, I know this is fast, but I just was wondering, because I feel like we've got something… something good and–"

"I want to," Jack assured him. He paused. "Are you really sure you want me around?"

John smiled. "Jack, I feel so… connected to you. It's odd, but I somehow feel that I… that I know you. You feel so right to me." He took Jack's hand in his.

"Okay," said Jack quickly, not allowing his brain to stop him. "I'll come." He tried to force the watch in his pocket out of his mind. Better to keep an eye on him, he told himself.

John grinned and kissed him. "Brilliant."

**

Jack had always liked traveling by train–one of the things he had grown to like during his time in the twentieth century. Still, he was having trouble enjoying this particular train journey.

"Everything okay?" John asked, looking up from his book.

"Oh, I'm fine," said Jack, trying to smile. "Just thinking." He went back to looking out the window.

"Is everything all right at work?" John took off his glasses and looked at Jack seriously.

Jack shrugged. "Yeah. Just… it's a rough transition. We… lost some people a while back. It's been a tough adjustment. New people on the team, you know?"

John nodded. "You're taking a well-deserved break. That's good. I've always admired the work you people do. It's a thankless job."

Jack had almost forgotten what he'd told John he did for a living. "It's very rewarding," he said absently, watching the countryside fly by. How long was he going to keep this up? He'd have to remember exactly what he'd told John about his job. Now he knew how Gwen had felt when she'd been lying to Rhys.

"How are things going with your work?" he asked John, in an attempt to change the subject.

John looked up from his book again. "I'm working on that proof; I wanted to get back and spend a few days on that–I've got this lecture to give next week. I'm sure you really don't care about that, though…"

Jack leaned forward. "Oh, I think it's really interesting." He gave John a toothy grin. John smiled

"Well, the fascinating thing about the Randall's Theory of Derivatives is…"

Jack leaned back in his seat. He could get used to this, just listening as that marvelous voice babbled on about who knew what. It was almost like traveling in the TARDIS, with one key difference–this man didn't have the weight of the universe on his shoulders, and Jack liked that.