My first Doctor Who story! My brother wanted me to write him a story about the Doctor that included Daleks and Cybermen but no Oods. Instead I wrote this. Enjoy! Any feedback is greatly appreciated. :)

Action take place post "Journey's End."

As always, I don't own anything. Just having some fun with the characters for an evening.

The Key

Donna Noble – also known as the Super-Temp of Chiswick - had a key. Of course, she had a lot of keys. Car keys, house keys, even those flimsy little keys from the journals she used to keep as a child. It wasn't remarkable that she had another key – it was remarkable that this key didn't seem to open anything.

She had found it in her pocket the night after the planets disappeared from the sky. In her haste to call Neris to catch up on the gossip that she must have missed while she was away – and she must have been away, how else to explain how she could have again missed something so massive? – she had set it on her dresser and promptly forgotten all about it. It was only a few days later, after her grandfather had assured her that really nothing spectacular had happened and her disappointment had dissipated, that she noticed the key sitting amongst the jumble of bobby pins and earrings on the counter.

She frowned, picking it up, really looking at it for the first time. It was nothing special, just a little silver key with a rounded top. It seemed at once alien and completely familiar. She had experienced this feeling before, when she was walking around town and thought she saw a friend from university in a crowd. The thrill of recognition zipped through her body until she realized that she was mistaken, she didn't know that man at all. That same thrill ignited her senses when she looked at the key. Something itched in the back of her mind, like the key should have been familiar but wasn't.

At first she thought it might be another car key. She and her mother were always arguing over the car keys and perhaps she had – in a moment of charitable generosity – had a second one cut. That would explain what she had been doing while the Earth moved through space. But her didn't fit in either the door or the ignition.

It didn't fit the house either. She tried the front door and the back. She even searched the house for any sign of a secret door, knocking about, driving her mother crazy. The family watched Donna with anxious concern – they had no idea how she might act if she was starting to remember. Any strange behavior might indicate that their worst fears were about to be confirmed and their Donna would burn before their eyes.

Her grandfather found her one morning, crouched on the front stoop in the midst of another futile attempt at jamming the key into the front door.

"Donna, sweetheart, what are you doing?" he asked, nonplussed. It wasn't every day that one opened the door, expecting to find the morning paper and discovered instead one's granddaughter poised to ram a key into one's navel.

Donna looked at him and flashed him an embarrassed smile. "Morning Granddad." She sighed and sat down on the stoop. He joined her.

"What's this?" he asked, motioning to the key.

She shrugged. "I don't really know. I found it in my pocket the other day and I have no idea where it came from."

Wilf took it from her fingers and held it up to sky, using the sunlight to illuminate any subtle markings. "You've never seen it before."

"Nope. No idea what it is. Maybe it goes to your paper stand? Maybe you gave it to me and I forgot. You know me – always forgetting something."

"I've only got the one key. This isn't it." Wilf handed it back to her.

Donna scowled. "I don't know why it bothers me so much that I don't know what it goes to. It just seems so useless."

"What do you mean?"

"Who makes a key that doesn't open anything? You don't. At least, I wouldn't."

Wilf reached down and picked up the paper from the stoop. He stood, pausing to rest a hand on her shoulder. "Don't worry about it, Donna. A child probably left it in the park and you picked it up. It's not that important."

Donna remained on the stoop, staring at that key. It had to be made for something. People just didn't make keys that didn't open anything. It had to have a purpose. It was important, to someone. She pulled her key ring out of her pocket and worked the mystery key onto it. Someday, she promised herself, she'd find out what it was made for.

A few minutes after he left Wilf in the rain – or maybe it was ten thousand years – the Doctor realized he had made a mistake.

He had meant to erase everything. Every memory, every thought, every subconscious retention of her travels with him. But he had forgotten the most tangible piece of evidence of all – the TARDIS key.

For a moment, he was at a loss. How could he forget? He had been so careful, so meticulous about ensuring Donna's survival. He had explained everything to her family, even been tempted to wipe their minds too, just to make sure that something didn't accidentally slip, ending Donna's life in a blaze of knowledge and majesty.

But ultimately, he had left the source of her downfall in her possession.

He leaned against the TARDIS' doors, his eyes drifting closed in defeat. How was it possible that he had managed to let down the one person who seemed to understand those dark places that his mind inhabited better than anyone? She had become a part of him – literally – and in his haste to protect her, he had been sloppy.

But his amazing Time Lord brain didn't allow him to sulk for long. Within seconds, he was replaying their last exchange, trying to pinpoint the moment when he could intercept Donna and gather the key without her noticing. Maybe if he snuck back into the house, while his past self was debriefing Donna's family, he could grab the key while Donna slept. It would be incredibly simple…

…Or it could be incredibly dangerous. Donna only had to awaken, or Wilf of Sylvia merely needed to turn around at the right moment, and the entire enterprise would be spoiled. Dare he risk a paradox to save one person?

If Donna had been sitting next to him, she would have told him it wouldn't be worth it.

"I'm just one person, Alien-Boy," she'd say. "I'm just a temp from Chiswick. My life isn't important enough to endanger the rest of the world's existence."

He smiled at the thought. That was Donna – the woman who wanted to save the world. And did. She'd never know that now, never realize how integrally important she was, not only to Planet Earth, but to the whole universe.

In the end, she had lived up to her name.

He jumped up, running to the TARDIS' consol. He couldn't get the key back, but he could check on her, just to make sure everything was alright.

Several months later, once the world had started to forget the Day the Earth Was Stolen, Donna Noble took her lunch to Trafalgar Square. Her latest job was nearby, a six-month engagement at a prestigious law firm. Her mother was openly enthusiastic that this job would become more permanent, but Donna didn't really care if it did. Something was missing.

She felt as though some vitally important part of her was missing, like trying to remember a dream that was just a hair out of reach. Closing her eyes, she leaned her face up to the sun. Now what was it?

When she opened her eyes, through the throngs of tourists, she saw a man. Unlike most of the people milling about on the square, snapping pictures and reading guidebook quotes to one another in stage whispers, he seemed utterly disinterested in the history around him. In fact, he seemed to be staring right at her.

She blinked. He wore a brown pin-stripe suit paired with a brown duster. On his feet were a pair of worn, white Converses. His dark hair stuck up in the front, as if he were accustom to running his fingers through it. His hands were deep in his pockets and he frowned at her. Not in anger, no, more in thought. He was studying her.

A tingle of recognition burned in the back of her mind. Her sandwich forgotten, she started to rise, to great him. She knew him!

At that moment, her keys fell from her lap, sticking the pavement with a sharp, metallic clank. She shook her head and reached down to retrieve them. When she looked up again, she had to laugh. She was doing it again, mistaking complete strangers for old school chums. She smirked and nodded to the man. One of these days she was going to make an utter fool of herself, running up to someone who had no idea who she was and hugging him like they'd know each other forever.

Across the square, the Doctor also nodded. Satisfied, he melted back into the crowd and in to time.

FINIS