I'll See You On the Long Way Round (Not Finished)

She's known the doctor since after his regeneration to 9, the battleworn man, still recovering from what he did. He said he'd be back for her, when she needed him most. They parted, after barely 100 years, she was left on her home planet of Sanguinia and he made the solemn promise to return. He's a new man and she's stronger, faster and wiser.

And he's coming back for her.