Major spoilers for Journey's End. I was feeling depressed about Donna's fate and how the Doctor was handling it (not well). I'm not totally sure about this, but I felt a need to write it.
Disclaimer: Despite my adoration for David Tennant, he is not and is not ever likely to be mine. Neither is anything else. :'(
He looked in on her from time to time.
She wasn't the first he'd gone back to like that. He loved watching his companions grow and blossom in ways denied to them while they lived in his considerable shadow. He loved seeing them smile and laugh, seeing their lives go on unbroken, better from their time together.
She wasn't the first, no, and she wouldn't be the last. But she was the hardest.
"And I said no way is she back with him, just who do you think she is? And he said I just didn't understand them, but he's such a bloody fool and just who does he think he's kidding…" Donna froze by the window, mouth open impossibly wide in shock… "No way," she screeched to her friend on the other end of the phone line. "I always said they'd end up together, just you watch…"
Her body was silhouetted against the open living room window, framed by warm lamplight streaming out into the night. She gestured dramatically, her expressions and exclamations picked out clearly to her observer.
He leaned against a lamppost across the street, arms crossed over his chest and an inscrutable expression on his face. The light breeze played with his overcoat, teasing the bottom away from his legs.
"…And I couldn't believe, I just couldn't believe he had the nerve to ask me…" She rolled her happy eyes and scrunched her face into an exaggerated expression of half-faked disgust.
A grin twitched at the corners of her observer's mouth as he recalled the same eye-roll directed at him as she blew off another of his clever suggestions. The swing of her arm as she punctuated her story brought images of the same arm swinging at his cheek, and he touched it gently with his hand, but the sting was long gone.
He looked away, allowing for a moment the images and memories to overwhelm him, the feel of rough red hair against his arm, a quiet, thoughtful voice that emerged more and more the more time she spent with him; a quiet, growing wisdom.
Then he pushed it away and looked back; the most important woman in the Universe was rocking with laughter on a chair, one hand still clutching her cell phone and the other thrown in the air in exclamation.
The ironic thing was, if anyone could have handled being him, it was her.
He smiled, but it was bitter.
Martha had become a soldier and a doctor. She fought for the Earth, defended it. Jack rewrote an entire organization, turned Torchwood into something good, turned the people who worked there into good people, selfless people who gave willingly so much to keep the Rift from destroying their planet. Rose had fought her way back from another Universe to save them all.
Donna Noble had fought for every inch she had gained. He watched her grow from a lonely, longing, spoiled young woman into someone wise, clever and mature who had saved a Universe.
And then he had taken it all away.
"… You just wouldn't believe the gall he had! I'm telling you…" Donna stopped suddenly, letting her sentence trail into silence.
"Donna? You still there?"
"Yeah…" She frowned, tilting her head to peer out the window. "Sorry, I thought I saw someone…" Far away, at the corners of her memory, a faint whooshing sound tugged at her attention. A face, a flash of a clownish grin a brown coat and a hint of blue light.
Donna shook her head. "Sorry, it's nothing," she said to her friend. Catching the phone between her shoulder and her ear, she reached up with both hands to pull the curtains closed.
"It's nothing at all."