For reference, this is before the End of Time. This is still (for now) the 10th Doctor.
The Doctor was tired, very nearly drained. The battle for the lives of an entire cluster of stars had been bloodless but complex, diplomacy helping for once. His reputation as the Doctor had made the Rigellan Empire cautious and willing to talk, but they had not been friendly and it had taken him weeks to get them to agree. He knew that their empire was already doomed by history, though. The Second Great Human Empire had already begun in that time and soon enough they would encounter the Rigellans and more or less take over by being a lot smarter.
"I need a cup of tea," he said and got up. As he steadied himself, he heard the phone on the TARDIS control center ring and he groaned. "Why now?" he muttered darkly and picked up the phone. "If this not a major emergency then I am going to disconnect this phone," he said into the mouthpiece.
"It's about Donna," Martha Jones said and the Doctor suddenly forgot his exhaustion.
"What's happened?" he asked sharply. "Is she alright?"
"As far as I know, yes," Martha said reassuringly. "But her grandfather is a bit nervous about someone she's working for. Apparently she does some work for Torchwood and Donna is her assistant." She paused and the Doctor closed his eyes, knowing that something more was coming. "Doctor, he said that this Dr Rachel Anne reminded him slightly of you."
"What?" the Doctor said.
"He couldn't really say why, but he was sure of the resemblance." Martha hesitated again. "Could she be another regeneration of you?"
"I don't know," the Doctor said and sagged against the control panel. "I doubt it, but it is within the realm of possibility. Regenerations can be a bit random, though this would be a new one for the books."
"Can you come take a look?" Martha asked and the Doctor swallowed hard.
"If I met myself, that could be very bad," he said and shook his head. "You'll need to find out as much as you can about this Dr Anne and send it to me." He paused and added; "And please remember that it may not be me. If she resembles me, she may be a Time Lord in hiding." He didn't have to add the fact that she could just as easily be the Master's regeneration as his.
"I'll do my best," Martha promised. "By the way, I missed you at my wedding."
"Sorry about that," the Doctor said slightly sheepishly. "A very nasty fault in the TARDIS sent me into the path of an intergalactic armada and I was too busy to remember."
"Try to remember, next time," Martha said and the Doctor blinked at that.
"Next time?" he repeated slowly. "Is there likely to be a next time?"
"Just as a matter of course," Martha clarified. "I'll be in touch."
"Good to know," the Doctor said and heard her ring off. He started to wonder about the name but his body told him in no uncertain manner that it was going to collapse if he didn't rest.
Donna Noble was still rather puzzled by the fact that she had been a bloke, and not even human, but she had to admit, the evidence held together. The dreams certainly fit together, the ones with murderous pepper pots and flying creatures that tried to eat her and her hands moving to do things she only barely understood even then. The Rani, as she somehow knew was her employer's name, had identified several of the things, though she had kept her from breaking the walls of her memory so as to keep her alive.
"You know," she said aloud. "I always thought that I was nothing much, nothing special." The Rani nearly choked on her biscuit at that and Donna grinned back. "Maybe that was why I never thought that those dreams were real. I never thought I could do things like that."
"Probably a defense," the Rani said. "With Gallifreyan facilities, your recovery would be easier but this is hardly impossible." She looked at the calendar and then chuckled. "If we work hard, it'll be a Christmas present," she added. Donna looked at the calendar and chuckled as well.
"That's something to be celebrating about," she said and stood up briskly. "You think that I can help?"
"With the new memory blocks, you should be able to help with most of the machinery," the Rani said and stood up as well, slurping up the last of her tea. "If you start getting a headache, warn me and I'll take a look." She gave Donna a stern look. "We can easily take our time, so don't overwork yourself." Donna gave her an affronted look.
"Would I do something like that?" she asked and got a firm nod in response. She conceded the point. "Let's get to work."
Martha Jones was busy at her desk when she heard the email alert. She looked over and nodded as she took in the information. On the surface, Dr Rachel Anne seemed a bright but otherwise normal person, working on several 'black' projects for UNIT and Torchwood. She even had an academic record that was quite impressive and thorough. So why did Martha hear alarm bells whenever she looked at the identification picture?
"There's something wrong with her eyes," she muttered to herself. They were too bright, and she could see why Wilfred Motts had thought of the Doctor. But even so, the records were quite thorough. Then she looked down at the personal comments and saw a red-flagged entry. She scrolled down and stiffened, seeing the reference to 'an old fob watch that she carried around, discarded after being struck by a Dalek beam weapon and deflecting the attack enough for her survival.'
"Professor Yana had a long life as a human," she muttered and then shook her head. There was something important she was missing. This person was not the Master, since she was fairly sure that he would have moved against the Doctor already and Dr Anne had simply returned to her job afterwards. She scrolled down and saw the citation for bravery, drawing the fire of the Daleks to get the civilians out of danger. That sounded like the Doctor. But why would he become human again? She needed to get this to him as soon as possible but the situation seemed to be safe enough. Donna had not seemed to regain her memories and the Doctor, if that was who it was, would not want to harm her. He may have even hired her to keep her safe. Martha sighed in irritation. If she met this Dr Anne, she might trigger Donna's memories so she would have to send someone else. It was almost time for Dr Anne to be interviewed about her security clearance and Martha could get one of them to interview Donna Noble for those purposes.
I hope you enjoy this update. The plot is thickening.