"Nonononononono!" the Doctor exclaimed, wildly hitting keys. "No! No! It can't!" He stepped back, staring at screen on the console. "Oh, I can't believe it! It is!" And he went on mumbling, too quickly and softly for Sam to follow.

Sam wasn't sure how long he'd been watching the Doctor. He couldn't keep a sense of time in here. Martha could have left an hour ago, but for all he knew, it had been three. Possibly even more—he'd been plying the Doctor with questions for ages, although the Doctor didn't always explain things, too intent on fixing the timeline. Or at least that's what Sam had to assume. He hadn't taken his eyes off the Doctor, but he didn't know what the man was actually doing. He felt lost. He didn't know why he was here and he couldn't do anything now that he was.

"Doctor," he finally said, deciding that if the Doctor wasn't going to stop for a breath, he'd have to break in sometime, "is there anything I can do to help? What are we dealing with? What's happening?"

The Doctor ran his fingers through his hair, at first looking anywhere but Sam, and Sam had to wonder if the Doctor had even heard him. Finally, however, the Doctor settled his wild gaze on him. "Look," he said, removing his hands and leaving his hair sticking out at odd angles, "this isn't anything that I haven't had to do before. But, truth is, I haven't had to do it alone. The problem comes in modifying the process so that I can, because I need to pinpoint the key mutations and isolate them and—" The Doctor broke off. "But I'll do it, I promise you. It'll just take time."

"Do we have enough?"

"I'm not certain," the Doctor finally admitted. "And before you even suggest it, before you even think to mention it, because I know it has occurred to you, the answer is no, and you know why. I'll cause too much damage if I try to go back and fix this at an earlier point. I could save this parallel, or I could destroy it. And if I lost control, then there wouldn't be anything that I could do to regain it. Even if I'm careful, the chances of inadvertently setting off a paradox…." He shook his head. "It's not a risk I'm willing to take. Especially not with you. You're sensitive to changes in time now, more so than the average human and more so than even my companions become. Your travel is risky enough as it is; anything drastic goes wrong in this past, and you're liable to be torn apart. And," he added, "you're unique because of it. One person in two parallels. You weren't duplicated, Sam Beckett. You're a lovely little anomaly to this parallel. Well, you and me both. I'd thought it was a bit of a rougher landing than usual. Then again, usual being what it is…."

"And Martha?" Sam asked hesitantly. "Was she…duplicated?"

"I'm not sure," the Doctor replied. "I don't know when this diverged. It's still feeding off the same time, so I'm tempted to say no, but if this has been running alongside and just underneath us—relatively speaking, of course, because in reality, it'd be more apt to say it's running through us rather than even being superimposed on us, though that's still not precisely right—for a sight longer than I'd thought, then it's quite possible there's a Martha in this parallel who never encountered me. Or the Judoon, by extension. Or the plasmavore. Unless someone else intervened. Entirely possible, I suppose. But, yes, if there is another Martha Jones in this parallel, then things haven't been affected too much."

"Wobble hypothesis," Sam offered, going back to the Doctor's DNA analogy.

The Doctor grinned. "Oh, I like you, Sam Beckett. Yes. Like that. Silent mutation, neutral, no overall effect. But accumulative? We're looking at evolution, the formation of a brand new parallel world. Except, of course, for that nasty little termination codon that's upstream of us."

He went back to his work, but the silence was starting to get on Sam's nerves. "What did you mean, earlier," he asked, "when you said that you'd thought I'd remember?"

"I've met you before, Sam," the Doctor answered. He stopped his work, turning to look at Sam. "Not like this. I tracked you down this time. Mind, last time wasn't precisely a chance meeting, either, when it came down to it. But, I met you, and you told me all about Project Quantum Leap. And then we dealt with some aliens. My line of work, I suppose you could say, but I would've been in a spot of trouble if it hadn't been for you."

"Aliens?" Sam repeated. "But I remember that leap. Quite clearly. I never met the actual aliens themselves, just saw their spaceship. Twice."

"I didn't run into you on that leap," the Doctor informed him. "I ran into you on the next one. The one you don't remember. But I seem to recall something about Al not telling you about things you don't remember, and seeing as that's your own rule, I'll abide by it."

The Doctor started to fiddle again, but Sam stopped him, catching his arm. "Tell me," he said. "Why would I have told you everything?"

The Doctor sighed. "You thought I was another leaper."

"Like Alia."

"You hadn't met her yet," the Doctor said gently.

"They were using her. I…I tried to…get her out."

"You did the right thing."

"I don't know what happened to her."

"She's safe."

"How do you know?"

"I know."

"But—"

"You trusted me before. I can only hope to earn your trust again."

Sam couldn't argue with that. "But…if you were at the Project just now…."

"I can't tell you anything. You know that."

"I know, but…but I thought…." Sam shook his head. "Nothing's happened to Al, has it? I mean, if it had, Gooshie would have come, wouldn't he?"

"What?" the Doctor looked at him, genuinely surprised. "No, Al was fine. Well, the situation may have given him a bit of a headache. Well, me more than the situation. Well, me and the other me being the situation…."

Sam looked relieved, but then he became worried again. "But if Al's fine, why hasn't he come?" A thought occurred to him, and he demanded, "He's not visiting in the Waiting Room again, is he? Because the last time he did that, I nearly…." Sam caught his breath. "I nearly…. I changed history."

"You always do," the Doctor pointed out, but Sam had a feeling that he knew what he had been implying. "But, no. Reason Al hasn't come is because they can't find you."

"What?"

"You're in the TARDIS. Ziggy can't pick you up."

"You mean all this time I could've—? But I wasn't in here the entire time!"

"Yeah, well, they were a bit busy before that," the Doctor acknowledged. "I tripped the alarm when I ended up in the Waiting Room, and they were scurrying around trying to figure out how to shut it off." At Sam's look, the Doctor explained, "I put in an alarm. After last time. Just in case. It's…not time to tell that story now. Thing is, I showed up after that, and then I'm afraid I was monopolizing Al's time, trying to figure out why you'd leapt into me, and—"

"Why?" Sam interrupted. "Why am I here?"

"I don't know," the Doctor answered. "That's why I'm here. To find out what went wrong. And why. So you can fix it. And then I can go back and carry on my life as I should, and if I have to forget about you, then so be it."

The Doctor turned back to his work, this time crawling under the console to check on something. "And, Sam," he added, "there ought to be a key in your pocket if you decide to go out. Unless it's still around your neck." He poked his head out. "What was I doing when you leapt in? Well, no, you wouldn't know that, would you? I would've been gone by the time you leapt in…." He frowned, then shook his head. "No matter. Just make sure you have a key. I don't remember if I replaced the spare after I changed the locks. Had it stolen once. Nasty experience. Not one I want to go through again. Then again, it has come in handy. Like the time when the one I normally keep on me was stolen. So maybe I did. Replace it, that is. Don't recall."

"And you'll be finding out a way to sort all this out?" Sam asked doubtfully.

"Yup," came the cheery reply, slightly muffled again. To Sam, it sounded almost forced. "Though, if you do talk to Al, tell him to tell me—me, the other me, the leapee—that we appear to be in a continuous enantiomeric pocket of a Type LXXVI parallel."

"There're seventy-six types of parallels?" Sam asked.

"Actually, there're several thousand by that classification system," the Doctor replied. "And it was considered archaic by the time I came around, with the system that replaced it differentiating parallels into tens of thousands by their…." The Doctor trailed off. "No matter. You'll remember the names used by the archaic system better than if I were to tell you what was considered standard. And you can appreciate that it's a sight simpler than the system the archaic one replaced. But, do make sure that message isn't mixed up while you play telephone. A Type LXVII parallel is completely different from a Type LXXVI parallel. Part of which has folded itself into a continuous enantiomeric pocket. Specifically, the part in which we have found ourselves."

"If you're worried that the message may be skewed," Sam asked carefully, "why not deliver it yourself?"

The Doctor emerged a second time. "You're sharp, Sam," he admitted, and then his grin returned. "I like that. But, truth is, given the nature of the pocket, I'm not sure if I can get out. Not without causing some damage to the chronon strands. It will take some very careful manoeuvring to slip out without gnarling them, and I'm lucky I didn't do any more damage getting here in the first place."

"But if you can't leave, what makes you think that they'll be able to locate me?"

"I'm working on boosting the signal," the Doctor told him. "And am playing on the fact that you're an uncopied anomaly with a natural ability to bridge the parallels." He was quiet for a moment. "And I'm hoping," he added finally, "that we're very lucky, and that your presence isn't a catalyst."

"But then…." Sam stared at the Doctor. "But then I'll only make the situation worse. I'm here to fix things. You know that. I can't…I can't risk it."

"I'm afraid we don't have a choice," the Doctor informed him, clambering to his feet and straightening up. "This part of the timeline, this parallel, is going to end whether or not you go out that door. But if you go out that door, we may not have to fix this mess by ourselves. We'll have help. Or at least support. And information. If I can piece together the original strands, we'll be home free. But I'm going to need help."

"And that's why I'm here?"

"Yes."

"Then why didn't I just leap into Martha?" Sam challenged.

"Because I have more experience now than I did then," the Doctor replied easily. "Please, Sam. Continuous enantiomeric pocket of a Type LXXVI parallel. If I'm working at this from both strands, I'll be able to put it together. But I can't do that if I don't know what I'm dealing with."

"So I'm a go-between."

"Sam," the Doctor chided. But then he relented. "Perhaps you're right. You were last time. But whatever your reasons for leaping, you can help me now. If you're willing. Please. You leaped last time, Sam. I'll make sure you do again. I promise."

"But not home," Sam said, almost bitterly. "Never home." And, unwilling to face the Doctor, he headed out of the TARDIS. He wanted his suspicions to be denied, but he was too afraid that they would be confirmed to stay.

Because some small part of him knew that the Doctor did know whether or not he would ever get home.

"We've found him!"

Donna's joyful voice broke through Al's troubled thoughts, and he looked up. "Al, Ziggy's found him," she repeated, smiling through tears.

Al felt a weight drop off his shoulders. "Good," he said. "I'll be in the Imaging Chamber. Tell Ziggy not to waste a moment in locking me onto Sam, got that?"

"Understood, Admiral," Donna replied as her smile spread into a grin.

Al wasn't sure how it was possible, but he knew Donna worried more than the rest of them. And any complications they ran into on a leap, well…. It was irrational, but Al was fairly sure Donna blamed herself for every one. And not one of them could convince her otherwise.

Al breathed a sigh of relief when the swirling images around him in the Imaging Chamber settled and he saw Sam standing opposite him, looking in the other direction. "Sam," Al called, causing his friend to jump.

"Stop sneaking up on me!" Sam insisted, but then he laughed. "I was beginning to think you'd never get here. It's been hours!"

"We couldn't find you," Al pointed out. "Believe me, we were looking."

"The Doctor said it was because I was in the TARDIS," Sam admitted.

"The Doc—?" Al looked around. "He's here? Where is he?"

Sam glanced around uneasily. "I think…on the other parallel."

"The what?" Al checked the handlink, making sure he was hearing Sam correctly. Apparently, he was.

"The other parallel," Sam repeated. "It's astounding. According to the Doctor, the timeline has diverged into two distinct parallels. I leaped into the ot…but th…Al what's…on? Yo…ing up."

"Gooshie!" Al called. "What's happening?"

"There appears to be some interference, Admiral," came Gooshie's unsteady reply.

"Interference? With what?" Al demanded.

"We…seem to have some trouble determining that," Gooshie admitted.

"Well, crank up the power," Al hollered back. "I can't make out anything Sam's saying."

"We are, Admiral."

Sure enough, Sam's image settled down again. "Something's going on," Al informed him. "I don't know how long we have."

"The Doctor must have known it would be difficult," Sam said, more to himself than to Al. "That's why he was boosting the signal."

"Sam," Al broke in, "what are you talking about?"

"Parallels," Sam answered. "It's amazing. In all the leaping I've done, we've never run into something like this."

"Great," Al said, hoping that if he started saying something now, he'd be saved from an explanation that made no sense to him. "But do you know why you leaped in here?"

Sam shook his head. "The Doctor says he hasn't figured it out yet, either."

"What do you mean, the Doctor?" Al asked. "You leaped into the Doctor. He's in the Waiting Room."

"I mean the other Doctor," Sam said. "He came back here. Didn't he tell you?"

Al frowned. "Of course not. Look, have you figured anything out?"

"The Doctor said to tell you to tell the other him that he thinks we're in a continuous enantiomeric pocket of a Type LXXVI parallel."

Al stared at him. "Come again?"

"The Doctor thinks—"

"No, Sam, I heard you, but…what?"

"As far as I can tell, the part of the parallel that I leaped into has twisted into a pocket," Sam began. "It's similar, but in some respects, it's like a mirror image. The two parallels aren't quite identical, I mean. They look similar, and for all intents and purposes, they are, but half of this parallel is synthesized. Half of it is a mirror image. And the Doctor says that he needs to put the original strands back together."

"Right." Al looked doubtful. "But he doesn't know why you leaped in?"

Sam shook his head. "No one seems to." He looked away for a moment and then back at Al. "He says I've met him before."

Al sighed. "You have."

"Tell me about it. I don't remember a thing about him, and he knows everything about me and the Project! You can't expect me to go into this blindly."

"It's your own rule," Al reminded him.

"I don't care," Sam shot back. "Sometimes rules have to be broken. Please, Al. You told me my name. You told me about Tom. When I desperately need to know something, you've been willing to overlook the rules before. Why not now?"

"I don't know half of what happened on that leap," Al told him, sounding rather exasperated, even to his own ears. "And the Doctor essentially cleaned out our files of it. It may have only been a few months ago, but I don't remember everything. Even if I wanted to, I couldn't give you an account of what happened. And you're going to be asking me things I can't answer."

"But—"

"I'm sorry, but I can't do anything." The handlink squawked, and he looked down at it, frowning. He hit it a couple times and rolled his eyes. "Great. The Doc's previous tinkering is still interfering. Look, our records are going to be spotty on this leap. And we're having a hard time keeping a lock on you. What did you want me to tell the leapee again?"

"That the Doctor thinks we're in a continuous enantiomeric pocket of a Ty—"

"Hold on," Al said. "Gooshie? Write this down, will you? Continuous antiomeric—"

"Enantiomeric," Sam corrected.

"Uh, make that enantiomeric. Continuous enantiomeric pocket in a…what?"

"Type LXXVI parallel," supplied Sam.

"In a Type LXXVI parallel," Al repeated. He looked back at Sam. "I need to see what the Doctor makes of this," Al told him, "but I'm coming back." He punched the appropriate code into the handlink to open the door to the Imaging Chamber.

"Al, wait," Sam called, reaching out a holographic friend to stop him from leaving. "The Doctor said one more thing."

"What?"

"That…." Sam trailed off. Al waited, wary now. "That he thinks I can bridge the parallels, but that he can't. So he's not going to make it back to the Project until this is over, from the sounds of it."

Al knew Sam well enough to know that that wasn't what he had originally intended to say, but he also remembered how far he'd gotten last time he'd tried to figure out what Sam was hiding from him. He decided, against his better judgement, to let it go—for now. He nodded.

"Goodbye, Al."

"Yeah. Yeah, we'll be seeing you." Al stepped through and closed the door to the Imaging Chamber, more anxious leaving it than he had been entering it.

The Doctor had said that Sam was in trouble. More than once. And they'd had a hard time maintaining their lock on Sam once they'd finally found him. In Al's book, that didn't bode well. And he had to wonder what Sam wasn't telling him. Sam wouldn't deliberately withhold any information that would help them leap him out of there, but he might….

No. Al wasn't even going to think that. Sam got out of whatever situation he'd leaped into. He always did. And he was right; failure didn't necessarily mean that he was stuck. He'd either leap sideways or he'd leap on. But he hadn't failed yet, not that they hadn't been able to fix before it was too late.

Besides, if it wasn't something he could fix, he wouldn't have leaped in there in the first place.

At least, that's how it had been every other time.

But Al knew all too well, even from the last time they'd encountered the Doctor, that there was a first time for everything.

A/N: I'd just like to thank my reviewers (of which there have now been three different people, with Questfan being so kind as to drop me a note every chapter thus far) and admit that if you've read through Patchwork and are working your way through Splintering and have been silent throughout, I would like to hear what you think—suggestions, criticisms, compliments, the lot of it. Feedback is helpful, after all.