Author Note: I fully realize the song I was inspired by for this fic is meant to be a romantic song. However, I thought it could be taken another way; this fic is NOT a romance, it is a friendship. If you listen to the song, each verse or two corresponds to roughly a section of the fic.

Song here: www (dot) youtube (dot) com/watch?v=E0yi7N0cxrU

Disclaimer: I do not own Doctor Who. I'd really just be happy with owning the Master.

She amazed him.

For more than one reason, if he would admit it to himself. He had never known another living being to understand him as well as she did, aside from the Master. It had only been a few weeks since she had become his latest TARDIS companion and he was in awe. If he was going to be completely honest, it had even started back when she had refused to go with him the first time.

"Just... promise me one thing. Find someone."

"I don't need anyone."

"Yes you do. 'Cause sometimes I think you need someone to stop you."

It was a funny thing, that. Rose and Martha hadn't understood him like Donna did.

He understood her too, though. He knew that she had never been treated the way she deserved, except by her Grandfather. He understood her deep affection for other people, her unwavering sympathetic personality. He understood and he adored her for it. It was one of the many things that made her such a joy to be around.

He called her brilliant because she was.

He amazed her.

She often wondered just how he did this, day after day, year after year. She always watched him rise up like a phoenix, the ashes of defeat still clinging to his wings. Even in loss, he was still the Doctor. He never gave up and he mourned every person that died, whether they deserved it or not. She always felt compelled to comfort him and he seemed to appreciate it immensely. And she never judged him. What would that solve? She couldn't have done any better than he did.

He always walked around the TARDIS with that barely perceptible shadow on his features, the shadow that very few could see. She could see it as clearly as if someone had taken a paintbrush to his face. He was always sad, even if he claimed otherwise. She knew he was forever haunted by the ghosts of his past, though what those ghosts actually were left her guessing. But she didn't press the issue. It was his own decision to tell her about things; she wasn't going to nag him for information about something he'd rather not talk about.

Even so, she sometimes wondered why he kept her around. She wasn't anything special. She was an ordinary human, clouded with her own fears and lack of self-esteem. That was why she was so afraid to come with him at first. She realized that the only reason her constant chattering wasn't driving him mad was because he talked just as much as she did. He never once thought her inferior just because she was a temp. He was fun to have around, of course. He was fun to travel with. He was mad and brilliant and wonderful.

She made the declaration of staying forever because she meant it.

Even when Donna was gone, she wasn't really gone.

She was in her room, in the kitchen, outside the TARDIS before he could stop her. She held a vivacity for life that he had only ever seen in a handful of humans. She enjoyed the adventure and the danger, despite the outrageous amount of running involved.

She knew why it was that he couldn't save anyone, despite the fact that he always wanted to. She could see how utterly broken he was and resolved to be the bond that held him together. She would give him hugs and soft words of comfort exactly when he needed them, as though he was an open book to her.

She cried when someone died, even people she'd never met. She held him when he wanted to cry, but couldn't.

She reminded him of a much brighter version of himself.

As time passed, she felt more and more at home. Earth was now a place where her relatives lived, but not her. She was perfectly happy in her blue box.

And she knew now that she'd never leave. It wouldn't have made any sense to people who hadn't traveled with the Doctor. Spending your life in a blue box sounded mad, but she didn't care. Life in the TARDIS was brilliant. It was danger and suspense and adventure. It was tragedy and sorrow and hope. It was... her.

Time passed and Donna stayed.

He often thought of the oddity that was Donna Noble.

More often than not when she wasn't around, of course. The wide expanse of the Earth alone briefly made him wonder just how she managed to find him again, the fond memory coming to the forefront of his mind. He sometimes frowned at the people who would brush her off as just another person, wanting to shake them and tell them just exactly who it was that they were speaking to. He had never believed in anything like destiny, and still didn't, but Donna's presence in the TARDIS was almost... meant to be there. She never complained, she never demanded, and she was always appreciative.

He had once tried to explain to her some things about the Time Lords. Random little tidbits, nothing so important as to get her to ask questions, but he had briefly touched on the subject of emotion. She had asked why the emotions of Time Lords were so different. He explained to her that they were far more intense, more vivid and encompassing than humans were able to feel. It wasn't until later that day that he realized his feelings of friendship toward Donna were ones of one Time Lord to another, deep and unwavering. He had a sneaking suspicion, as far as she was able to feel, that her feelings of friendship toward him were on a similar scale. Best friends, even.

He decided that she found him again because they fit.

She sometimes wondered why people thought of them as a couple. They were most certainly nothing of the kind, not ever. Perhaps it was because, somewhere deep down, there was an instinctive vibe from them both, one that said they belonged together. Most people would naturally jump to romance, but it was nothing of the sort.

The Doctor never took it for granted that she would stay forever, despite her insisting the contrary. It felt natural to her; being in the TARDIS was as normal as breathing.

It hurt, sometimes. It hurt to see them fight, to watch it burn, to see him cry. But she bore the same burden that he did: traveling to just one more place, to save one more life, even if it meant helplessly watching thousands of others perish, thousands they could not save.

He learned that he did sometimes need someone to stop him. She learned that she was so much more than just a temp from Chiswick.

They were partners in crime, a perfect duo. Almost too perfect.

He had always wanted her to stay forever.

He couldn't just let her die; it wasn't fair. Her tears and begging words only made it harder to take her memories away, wiping away the amazing person she had become. He knew she would have much rather died as the DoctorDonna than return to the way she was. He saw it in her head, the moment before he took it all away.

As much as he wanted to keep her, he couldn't.

So he wove a story for Sylvia and Wilf, of planets and billions of people who would be singing songs of Donna Noble for generations. Brilliant Donna Noble, who would always be more than just a temp from Chiswick. She was the most important woman in the whole, wide universe.

As he walked back to the TARDIS in the rain on that night after the Medusa Cascade, a thought crossed his mind that Donna had been the most important person in the whole universe to him too.