The Doctor's mind raced as he considered possible ways to destroy the Dalek. It had been easy last time; he'd had Rose with him. The Dalek in Van Stattens base, the fleet in the sky near Satellite five, the secret society, none of them had stood a chance when Rose Tyler defender of earth was with him.

At least this time he didn't have to worry about risking Rose's life. But maybe that was the only reason he fought so hard? After the Time War he'd promised himself that he wasn't going to interfere; he'd let nature take its course. Then Rose had stumbled in and everything seemed worth saving. Especially her. He'd sent her away so many times to keep her safe and each time she was determined to reach him and save him. He smiled at the thought.

"So how are you going to stop it?" The girl asked, bringing the Doctor back down to earth with a bump.

"What?" The Doctor looked up. "Oh, I'll think of something."

"Do you have any plan?" The girl said smoothing her clothes down.

"Nope," the Doctor admitted. "But I think my first stop is going to be Torchwood."

He glanced about to check the Dalek was out of sight and was just going to set off when he felt someone grab his wrist. He looked back at the girl.

"Let me come," she said desperately. He was going to refuse, say that he was more danger than the Dalek, but something in her petrified tone made him stop. Rose would've saved the girl. Rose would've wanted to make sure that as few lives were taken as possible. "Please."

"Ok," the Doctor grabbed her hand and ran across the street, ducking down another ally-way and heading for Torchwood Tower.

It took less than ten minutes to reach it, even with the girl behind him. As he glanced up at the now abandoned Torchwood Tower he suddenly realised he didn't know who the girl was.

"What's your name?" The Doctor asked pausing for a moment. The girl panted, catching her breath before she answered.

"Martha Jones," she replied. "You?"

"Wouldn't believe me if I told you," the Doctor said smiling wryly. "Nice to meet you Martha, run for ya life!"

He took her hand again and the pair raced the steps and into the building.

"You can't not tell me!" Martha complained but she was too worried about the Dalek to care too much.

"Well, my human name would be John Smith," the Doctor continued. "But to my friends I'm known as the Doctor, and to my kind, the Time Lords, I'm called Theta Sigma, or at least that's what it would sound like to you."

"Whoa, slow down," Martha said frowning at him as they continued up and up until they reached Yvonne's office. "Time Lords?"

"Yeah, I'm alien," the Doctor pulled out his glasses and pushed them onto his nose, typing frantically at the computer. "Come from a planet along way from here that was destroyed in the Time War, a war between my people and the Dalek's. A few days ago I was here, when the Cybermen and Dalek's passed through this crack in time and space and I had to try and end the Time War once and for all. It cost me though. I've not only lost my home, family friends, but now…"

He stopped rambling realising what exactly he was saying. Usually he wouldn't go that far because Rose would stop him, but Martha was just looking at him as though she wanted to know more.

"Now?" Martha asked gently wandering towards him. He didn't look at her, just continued to type, searching the computer files.

"It took my soul mate," the Doctor said quietly. "And it was all my fault."

"I'm sure that's not true," Martha said sitting next to him at the computer. The Doctor found it odd that she hadn't questioned anything he'd told her.

"You weren't there," the Doctor replied mournfully. "I have a time and space machine, I can go anywhere, any when, but I always take one constant companion. Death."

Martha laughed then and the Doctor looked at her darkly. She covered her mouth in shock.

"I'm sorry," she said genuinely. "You just sounded so melodramatic."

The Doctor rolled his eyes huffily and returned to the computer. Martha sighed and leant on her arm.

"I really am sorry," she said. "I didn't mean to laugh."

"No, laugh all you like," the Doctor shrugged. "That's all I am, one big joke. Even the universe thinks so. I've had everything taken from me so someone must be getting a kick out of my misfortune."

"Oh come on," Martha frowned at him. "That's not fair."

"Life isn't fair," the Doctor said darkly, finding the file he needed and reading it. "Get used to it."

The Doctor stood up and stopped when he caught sight of the wall that was the weak spot in time and space, where the opening to the other universe was.

"You're harsh," Martha said disgustedly, shoving past him and heading for the door.

"You'll die if you go out there," the Doctor said a little softer.

"Better than being stuck in here," Martha shot back. The Doctor was stung by that remark.

"I'm sorry," he said his voice cracking. Martha looked back and saw how sad the Doctor was. "I snap when I'm under pressure, or upset or angry."

Martha nodded.

"S'ok," she said standing in the doorway.

"I saw her disappear here," the Doctor whispered looking back at the wall. "When her gaze locked with mine we both knew it was over. There was nothing we could do, but it doesn't help the feeling of knowing that it was my fault."

Martha wandered back to him and touched his arm gently.

"Who was she?" She asked in a hushed voice.

"The stuff of legend," the Doctor said smiling slightly. "My soul mate; Rose Tyler, defender of Earth."

He sighed again and glanced down at Martha.

"C'mon, we've got a world to save," he said and the pair headed back the way they'd come and towards one of the Torchwood labs.