Jack was very glad he was alone when the familiar noise started up, coming from the basement. Not, he thought gratefully, the basement where the Weevils were kept. The other basement. The one where Ianto'd been keeping a Cyberwoman for months.

He almost picked up his gun out of habit, then left it and started bolting downstairs. He burst in the door just as the Doctor stepped out of his door, and couldn't help a grin. "You turned up! You know this place is supposed to be protected from any kind of teleportation."

"I hacked it."

"Unsurprising. So, trouble brewing or could you just not resist me," Jack started to ask, and then looked, really looked, and blinked.

He didn't look – different, exactly. Definitely the same face, and he didn't seem any thinner or paler or any of the usual signs that would have yelled 'unwell.' But Jack was still getting a shouting feeling of 'unwell' from the Time Lord anyway.

Jack frowned, barely, and then realized the second problem he was having. "Well? What's taking the others so long?"

"Others?" The Doctor said blankly, and then shook his head. "Oh, right. Others. …Jack, can we go upstairs? Maybe outside? I don't…this feels too much like a space station."

"What's wrong with space stations?" Jack asked, and then added, "And where are they?"

"—not here right now," the Doctor said, after a moment. "It's just me." And Jack really started to get concerned.

They went outside and sat on the sidewalk, and the Doctor was quiet for five full minutes that Jack deliberately counted, which was longer than he could ever remember the Doctor being quiet for, particularly this one. 'Are you all right?' was a pointless question. So he tried again. "So…Donna and Rose, and the – other you. If they're not here, where are they? Saving the world without you?"

He meant it as a joke, but the Doctor's face twitched oddly and his shoulders hunched. "No…well, probably. Maybe. I don't know."

"What do you mean, you don't know?" Jack frowned. "They're traveling with you, aren't they?"

"No."

Jack blinked. "No? What do you mean, no?"

"I mean, 'no.'" The Doctor's voice was tight, too tight. "They're not traveling with me."

Suddenly worried, Jack asked, "Are they okay? Safe?" Alive? No, Rose had to be alive or the Doctor would have looked much worse than this. Probably. Unless he was keeping it all bottled up inside, like usual. Jack felt his stomach lurch. "What happened?"

"Nothing, nothing." The Doctor sighed, and didn't look at Jack. "Rose and – the other me, the metacrisis, are in the parallel world. Closed off."

"What happened? Did it close too fast when you were taking Jackie home? I don't-"

"I left them there," the Doctor said, cutting through Jack's voice even though his own was quiet and barely audible. "Intentionally. The metacrisis will – grow old and die. With Rose. She's with her family, and she has – well, me. It was for the best."

Jack wondered just who it was best for, and asked, even more carefully, "And Donna? She's…"

"All right," the Doctor said. "With her family too."

Donna, Jack thought, would never have left. And the DoctorDonna even less. Not voluntarily. "What happened," he said, and he could hear his voice turn to steel. The Doctor looked at him, and his expression was so old and so angry that all Jack's steel shattered.

"Don't," he said. "Just don't. I didn't have a choice. Having a Time Lord consciousness in a human brain was killing her. I wiped her memories of me so that she would survive."

Jack shook his head. "So she doesn't know any of it, any of what happened, any of what she did?"

"No," the Doctor said, and his voice was still flat, emotionless. "She doesn't."

"And you," Jack said, his voice trembling, but the Doctor turned on him, on his feet and suddenly towering.

"Don't you dare," the Doctor said in a voice Jack had never heard before, a voice that was like the eyes he'd glimpsed a moment before, old and terrible and insane, a voice like the eyes that reminded Jack of someone else. "Don't you dare tell me that she wouldn't have wanted it. I know that. She begged me, it was the last thing she said, begged me not to do it. I did. I would do it again. I saved her life, isn't that worth anything at all? Doesn't it matter that she's alive because of me, because I would rather see her alive than be selfish and let her die because of me? Let her be ordinary, let her be happy, let her live-"

"Doctor," Jack said deliberately, because he was almost worried that if he wasn't careful Master would come out. "Calm down. I wasn't going to say – any of that." He'd thought it, but he wouldn't have said it. "I wasn't going to…I was just going to ask. About you."

The Doctor's anger winked out like it had never been there, and for a moment he looked almost frightened. He took a step back. "I'm sorry," he said, suddenly, "Jack, I'm sorry. I shouldn't have come here."

He's not stable, Jack thought, and winced. He'd seen before what an unstable Time Lord could do. But this was his friend, and something was wrong. "No," he said, and patted the sidewalk. "I'm glad you did. Really, I am. Sit down."

The Doctor sat, but he wasn't looking at Jack, and there was a slight distance between them now. "I've been traveling alone too long," the Doctor said in a quiet voice, and Jack nodded, briefly.

"I think so. I just wanted to ask. Did you know…when you dropped me and everyone off, did you know what you were going to do? That you were going to leave Rose in the parallel world and have to wipe Donna's – mind?" He couldn't be that angry about that, it occurred to Jack. It would be too hypocritical. How many minds had he essentially wiped with the RetCon?

The Doctor gave him a strange sideways look, and then just nodded. "Yes, I knew." There was another long silence as Jack waited for more, but none came.

"I didn't know you were going off on your own," he said, finally. The Doctor looked at him, but at least this time Jack recognized his eyes.

"Don't I always, in the end?"

He sounded so – unhappy. Jack frowned. "How long has it been? For you?"

"Eight months," the Doctor said, simply.

"You've been alone for eight months?"

"I've been alone for a lot longer than that," the Doctor said, strangely, and Jack looked at him and frowned. It was still there. Something had changed, something very bad had happened, and it was worse than just losing Donna and Rose. Something that had left his friend apparently on the verge of cracking.

"I'm going to die soon," the Doctor said abruptly. Jack stared at him.

"What?"

"It's a prophecy. 'He will knock four times.' And then I die." The Doctor laughed, a small, strange, shuddery sound. "I don't know when. Just soon. The Ood said it too. I thought after…but no, I guess not." He took a deep breath, and asked, "Jack, do you know who Adelaide Brooke is?"

It was a complete non-sequitur, but with the Doctor Jack was used to those. "Yeah, she was the leader of the first team to colonize Mars. Bowie Base One, right?"

The Doctor smiled strangely, and asked, "Where and how did she die, do you remember?"

Jack shrugged, not quite following, but sure that this was somehow important. "Earth, right? She killed herself."

"Not always," said the Doctor, his voice even more quiet, and Jack frowned at him, but no more was forthcoming.

"Doctor," he said, deciding that it was time to ask. "What happened?"

"Terrible things," said the Doctor, and he turned his head and smiled, again that strange and hollow expression that Jack did not like at all. "The Time Lord Victorious."

"What does that mean?" Jack asked. "Is that the Master, or something? Is he somehow back?"

"No," the Doctor said, "Not the Master, Jack. Me."

Jack thinks of the Doctor's face just moments ago, and half turns. "What happened?" He asks, but the Doctor stands with a sigh.

"I should go," he says.

"Why?" Jack asks. "That much of a hurry? Where are you going?"

"I don't know. Anywhere." The Doctor shakes his head, almost smiles. "Nowhere. I shouldn't have come here, Jack."

"Why not?" He demands. "I think this is the best idea you've had in a while. Something went wrong, and I guess it was bad, and you're upset about it. So what's wrong about coming to a friend for help?"

"Nothing, just-"

"Just what, you're in a hurry? You have a time machine. Someone needs to be saved somewhere, you have time. Sit down. Why did you ask about Adelaide Brooke?"

"What – date is it?" The Doctor asked, not answering the question (as usual, as always). Jack rolled his eyes.

"August 24th, 2009. Answer the question."

The Doctor closed his eyes briefly, and shook his head, very slowly. "You should go. Be with your team."

"They're not here right now. It's the middle of the night and you're going to tell me what's going on."

"That's new," the Doctor says, and Jack is almost relieved to hear the wry note in his voice. "You telling me what to do. No, Jack. It – doesn't matter, anyway."

"I think it matters a lot. Matters enough to drag you back to this old planet, you had to have known that I'd want an explanation."

"Explanations," said the Doctor. "Always explanations. Later, maybe. If I see you again. If you want to see me again." He turned back toward the Hub. "I'm sorry, Jack."

For some reason, Jack had a feeling that he was apologizing for more than just not answering the question, and frowned. "Sorry for what? Why did you come here if you're not even going to say anything?"

The Doctor turned and looked over his shoulder. "Just sorry." He smiled, that weird, sad expression that made Jack's stomach turn. "I just needed…I don't know, really. Stupid idea, one of many, I've had a lot of those lately. Gwen, Ianto – don't tell them I was here. Don't need to know, I just wanted to – well, never mind. Shouldn't have come."

"You're not making any sense. Are you all right?" Jack asked, and then sighed, because he knew the answer to that question, and it was no answer at all. The Time Lord barely paused as he walked back to the front door.

"I'm always all right," he said, and it was such a lie, such an obvious lie, that it wasn't even funny.

There were any number of things Jack Harkness could have done. He could have gone after the Doctor, asked again. Could have hit him over the head with something and kept him there for a few days until he talked about whatever was wrong, for his own good, or at least until Jack was sure there wasn't another Master walking around the universe. Could at least follow him and say goodbye.

He stayed until he was sure the TARDIS would be gone, and then went back inside the Hub. He shuffled a few papers half-heartedly, glanced at a few screens. Went down to the basement. It was empty.

The Doctor was gone again.