The next few days were interesting. They moved slowly, which was fine with Jack–he was still a little unsure of himself and it was strange that this territory was at times comfortingly familiar and startlingly alien. They didn't progress much past kissing, however, and Jack wasn't sure whether it was himself or the Doctor who was holding them back.

Despite all this, they were still traveling with Melody. They went to see an erupting volcano (once the Doctor had made sure it wasn't one Jack had visited during his time as a conman) and the Blue Moon of Gyro. Euclid was sort of a bore, and it would up being the Doctor who turned him on to the commutative property.

"What happened to not interfering?" asked Melody, as they made their way back to the TARDIS. Euclid had been at a party and they'd stayed rather late–Euclid may have been a bore, but his friends were fun. "That's the first thing you said about Time Lords–sworn never to interfere."

"Oh, that's the old days!" exclaimed the Doctor. "New days... well, he needed a little shove in the right direction."

"He had associative and distributive," offered Jack.

"Exactly!" said the Doctor, grabbing Jack's hand and swinging it back and forth. "Two out of three ain't bad."

Jack grinned and squeezed the Doctor's hand.

When they'd reached the TARDIS again, Melody went to bed early, leaving the Doctor and Jack standing together in the console room.

"Did you have plans for the rest of the evening?" the Doctor asked casually.

Jack shook his head. "Do you?"

The Doctor took a few steps toward him. "I was thinking we could spend it together," he said softly.

Jack looked away. He wasn't sure he was ready to go that far. He cared deeply for the Doctor, but part of him still wondered if he was betraying John.

"I don't know," he murmured.

The Doctor placed a hand on his chest. "If you're not sure, we don't have to," he said seriously.

Jack shook his head. "It's not that, I just…"

"Just what?"

Jack took a step back and ran a hand through his hair. "I don't know," he said finally.

The Doctor nodded and took a step back, though he seemed somewhat reluctant. "Fine, fine, that's fine." He stuck his hands in his pockets. "I've actually got some work to do." He gestured vaguely at the console. "Always work to be done. Good night."

"You sure?" asked Jack, as he made to go.

"Sure, I'm sure!" said the Doctor, turning a dial. "Whatever you want, Jack, I'm fine with that."

He didn't sound fine, but Jack left it at that and went to bed. Things were much better the next morning; the Doctor didn't allude at all to their conversation the previous night. When Jack came into the console room, the Doctor gave him a quick kiss.

"We're going to the beach today!" he proclaimed, grinning.

"The beach?" asked Melody incredulously, coming into the room.

"Yes, the beach!" The Doctor turned back to the console and fiddled with something. "I love a good beach."

"And it's just a beach?" asked Melody. "No sand monsters, no sharks?"

The Doctor cocked his head. "Why did you jump straight to sand monsters?"

She shrugged. "Thought you'd prefer sand monsters to sharks."

The Doctor grinned. "That I do. You're getting to know me well." He sprang toward the doors, indicating that Jack and Melody should follow. "I think we're just in time to see the sunrise. The beach at Rab-ele-roo–that means prism." He pulled the doors open and led them out onto the planet.

"Oh, it's lovely," Melody breathed.

The Doctor smiled. "Isn't it just?"

Jack had to admit the sight was beautiful. The rays of the rising sun hit the sand in such a way that it gave the beach a rainbow effect.

"It's the sand," the Doctor explained as the three of them walked toward the ocean. "Each grain has a highly crystalline structure, which causes the prisming effect. Combine that with the particles in the atmosphere–see those purple clouds?–and it makes the sunrise especially brilliant. Sunset's just not as nice, it's all the wrong angles."

Jack nodded. He was remembering the time he'd spent on the beach with John. The Doctor seemed to realize this and he gave Jack's hand a gentle squeeze. "Other places, though," he added, "have quite nice sunsets."

When the sun came up fully, the Doctor decided they could make a day of it–somewhat reluctantly, Jack noted, as the Doctor looked like he would probably much rather have had an afternoon of running from something that wanted to eat them than an afternoon at the beach.

Jack settled down by the TARDIS, watching the surf come in. The Doctor and Melody were further down the beach, collecting shells. He sighed. He knew the Doctor was trying, but he still couldn't help part of him missing John. Would this be an impediment to their relationship? He thought about the night before. The Doctor had seemed so disappointed when Jack had gone to bed alone and he hated to see that look on his face.

"What are you thinking?" the Doctor asked suddenly. Jack jumped. He hadn't even noticed the Doctor sit down next to him.

The Doctor had his trainers off and was wiggling his toes in the sand. It was very distracting. He followed Jack's line of sight. "Oh. Foot man, are you? Or just an everything man?" He lay back and rested his hands behind his head. "Personally, I'm… oh!" He sat up again. "Sand. I've got… sand… down my shirt." He shrugged off his suit jacket and began furiously shaking it out.

Jack laughed.

"Oi!" cried the Doctor. "Don't laugh at my misfortune." He grabbed a handful of sand and lunged at Jack. He ducked out of the way, but the Doctor caught the back of his coat and pulled him down toward him, flinging the sand at him. Jack was still laughing.

"You're terrible," said the Doctor. He lay on top of Jack and brushed some sand off his forehead. "Terrible and full of hormones. Love humans! You're so… open."

"Oh?" Jack raised an eyebrow.

"Yup," said the Doctor. "I know exactly what you're thinking. You're thinking about me, you're thinking how you're still not positive about all this."

Jack sighed and turned his head to the side so all he could see was the blue wooden side of the TARDIS.

"It's not that," he finally said.

"You still aren't sure I really mean it," the Doctor continued. "Or rather, you aren't sure you really mean it. Because it's not that you think I'm lying, it's that you think you think you're betraying someone."

Jack turned his head back to look at the Doctor. His brown eyes were warm and serious. "You know, Jack, the commutative property goes both ways."

Jack blinked. "What do you mean?"

"I like you and John Smith liked you." He slid his fingers into Jack's hair. "And you liked John Smith and you like me." He lifted his head, looking at something behind where they were lying. "Human or Time Lord, it seems always seems to come down to you and me."

Jack didn't say anything.

"And we are the same man." The Doctor took a deep breath. "Really. I told you before that I was capable of anything he was, but that's not strictly true. I can't have a normal life. But neither can you."

Jack flicked his gaze away.

"What were you going to do?" the Doctor prompted. "When he realized you didn't age? When he realized neither of you existed? Even in a month, he knew you were lying to him. You'd never be able to live a life with him. Your life would come crashing through and destroy his. It did."

"I know," said Jack.

The Doctor's gaze returned to Jack's face and Jack found himself succumbing to the pull of it, locking eyes with the other man again. "He certainly didn't want to change back, he wanted to stay with you. And in a way, he's getting the chance to. Because I remember everything, Jack. I remember how he felt about you, because those are my feelings. The time we spent together is just as much a part of my memory as anything else I've ever done. I am John Smith, fully and completely, except I can share this type of life with you."

Jack kissed him. The Doctor seemed surprised at first, but he welcomed the kiss enthusiastically, tangling his hands in Jack's hair. Jack wasn't sure if it was minutes, hours, days, weeks that passed, but they were both breathing hard when they broke the kiss, and then the Doctor kissed him again.

Again, Jack lost track of time. He vaguely remembered the Doctor murmuring something about going back into the TARDIS, remembered them leaving the door open for Melody and the Doctor saying something about giving her a key later.

But then they were in Jack's bedroom and he was kissing the Doctor again, had perhaps never stopped kissing him since they were lying on the beach. The Doctor's hands were moving, divesting him of his braces, unbuttoning his shirt after a whispered request for permission.

Jack was overwhelmed. This was at the same time nothing and everything like being with John. It was exploring familiar territory for the first time–that spot on his neck still made him hiss, so he kept nipping at it until the Doctor practically melted in his arms. There were other spots, spots that John had loved to have attention in that did nothing for the Doctor, and then were wholly new spots that made the Doctor cry out. Jack knew he wasn't going to rest until he'd found every one of them, especially, as the Doctor seemed to know everything about Jack, knew exactly what he liked, a fact he proved over and over again.

It was hard to comprehend that this was the same man, he thought after, as they lay in a tangle of limbs and sheets. The same hair was tickling his chin and the same arm was draped over his waist, but he could feel the beat of two hearts against his chest.

He pulled the Doctor closer, absently rubbing his back.

So the Doctor did actually sleep. Jack smiled to himself. He was looking forward to finding out all these things he hadn't known.

He closed his eyes. It seemed so peaceful lying there together, quite different to the hectic life they lived outside of the TARDIS.

Maybe this meant he could have some of the life he'd had with John with the Doctor. Not entirely, of course–the Doctor would never settle down, and Jack wasn't even sure he wanted to, either.

But there were the quiet moments, like this one, and as Jack lay there and listened to the Doctor's shallow breathing, coupled with the hum of the TARDIS, he realized this was the right thing, intrinsically. They had always loved traveling and they always would love traveling and they'd do it together.

It had a correctness to it, this life, Jack thought, a correctness so absolute that it was almost, well, mathematical.