After the Time War, pain had kept the Doctor from reaching out. He'd stayed alone, found excitement, got into trouble and got out again without particularly dreading the day it caught up with him for the last time. He hadn't fooled himself that he was happy--he didn't deserve to be happy. At least, alone, he wouldn't hurt anyone else.
When Rose had swung in and saved his life, his pride took over. She was brilliant, and he'd wanted to bask in that glow; but it wasn't safe for her. He'd given her every opportunity to leave and then he'd fit her into his mold: fantastic companion and best mate. If Jack hadn't turned up and stirred everything about, he'd have kept it that way--for her sake.
Instead, he'd let Rose and Jack into his privacy and they'd let him into their embrace. He still hadn't deserved anything good or any level of comfort in his life. Maybe that's why it didn't last. He'd lost Jack to the Daleks and his own fear and Rose to the sort of unfortunate circumstance they both seemed to attract.
The Doctor had gone to ground after that. By the time he'd accepted Martha as TARDIS crew, he'd fled so far into himself, she couldn't dig him out. First he'd been mourning, and then, just determined to be alone. Blimey, he'd even missed her falling for him--great big brain and he'd missed it utterly. Maybe he couldn't bear to see it, so he didn't. Even so, it should have spared her the kind of pain Rose must have gone through. It should have, but it hadn't.
"She's different, now. Harder," he said, as he wrestled a connection back into place. "And it's my fault."
Jack was ninety degrees around the console, stripped to his shirtsleeves and patiently doing delicate splices mostly by touch, his arms sunk to the elbows in the TARDIS's innards. He didn't answer right away. He wasn't as rash as the lad the Doctor remembered from his previous regeneration--not that the last year wouldn't have taken some of the impetuosity out of the most intrepid soul. When he did answer, he said, "Doctor--being with you doesn't harden us. Haven't you figured it out by now? What hardens us is being without you. You said Rose meant to work for Torchwood in the other universe. What do you imagine she's like, now? It's not your fault."
The Doctor swallowed down guilt and tried not to think about it. The notion was an entirely different order of horror than the last year. It would be so much easier if he were the one who died, so this trail of damage and hurt he seemed to leave behind him would finally end. But somehow, he always survived.
He couldn't regret anything he'd suffered at the Master's hands--he'd accepted it as the price of helping a suffering friend, even one who, in his madness, had chosen the Doctor for an enemy. And now, the Doctor had to live with the memory of the Master dying in his arms. He'd been avoiding sleep--he recognized the signs in himself. He wasn't sure what would bother him more: losing the other Time Lord again in his dreams, or waking up expecting a tent over his head and wondering if he'd just heard a bell. It was so important to move with alacrity when he heard that bell . . .
The thing he dreaded, the thing he loathed, was what others had suffered because he'd tried to save the Master. Simple, brilliant humans. He'd discovered that pride was no barrier if he could stop their suffering for his actions--and he couldn't, sometimes. To spare the cooks and masseuses and laundresses aboard the Valiant the Master's wrath, he'd learned to move to the sound of that bell. To keep Tish Jones from being thrown to that scummy mass of guards pretending to be UNIT and who found delight in their new vocation, he could and would drink from a dog bowl. And if he could have done anything to spare Jack pain, he would have.
Jack forgave him. Jack loved him. Somehow, that made the guilt even worse. What's more, Jack had fought the same battle more successfully--protecting the others subject to the Master's whims whenever he could--by virtue of being a more entertaining victim and causing the Doctor more pain with his suffering.
Guilt finally drove the Doctor to bed after the TARDIS shocked him for the fourteenth time. "Doctor," Jack said, gently, "you're tired. You're clumsy with it and you're hurting her. Even Time Lords need sleep, now and then."
The Doctor stopped dead and drew his hands to his chest. "I'm not afraid to sleep anymore, Captain," he said, wryly, and slithered out from under the console. Nightmares held no fear for him now--they were just his due. "It's the waking up I don't relish. Stop when you're done with that bit--I won't have you mucking about with my ship because you think you know what you're doing while I'm not here to keep you out of trouble." He stood up without facing Jack, so the impossible human wouldn't see his face while he hadn't control of it, and walked away.
Because his life was perverse, sleep ran from him when he lay down in bed and pursued it. The Earth turned under him and circled its sun, galaxies collided and stars came together out of dust, and he kept seeing the terror of the Swiss representative's daughter and hearing Jack's mocking voice challenging the Master. He started translating The Tempest into Gallifreyan in his head, trying to lose memories and awareness in the challenge of transmuting the Bard's words into an entirely inappropriate ideogramatic syntax.
One hour, twenty-four minutes and thirty-one seconds later, the Doctor's door opened. He didn't open his eyes as Jack stepped inside and closed the door. His breathing didn't shift as the Captain sat on the edge of his bed and he didn't make a sound as Jack slid beneath the bedclothes, T-shirt and sweats rasping against the fabric.
Jack reached out and drew the Doctor close against fever-heat that was human and an unignorable burr in the fabric of space-time that was not. The sensations were so alien--one hauntingly familiar, the other impossibly unique--that nebulae and Miranda and the Swiss representative's daughter went clean out of the Doctor's head. He leaned his forehead against a once-familiar shoulder, in a body that had never known the feel of the one pressed against his, and let Jack hold him while he fell asleep.