Disclaimer: the idea was sort of offered by koncussionkat, otherwise nothing here belongs to me.
A/N: first posted on tumblr

Time To Go

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"What about in there?" Donna suggested to the Doctor as they ran desperately through the power facility, down yet another corridor. "It should have at least one CCTV camera"

"Well done, Donna," he praised, and used his sonic to break into the security room she had pointed out. "We should be able to find the location of the correct panel now."

Once in there, he waved the sonic about, taking readings to aid their quest in saving the Firodorians from being blown to smithereens at any moment. The TARDIS had brought them there to stop an accident from becoming a global catastrophe.

After consulting the sonic, he frowned in confusion. "That shouldn't have happened. Somebody has already shifted the power flow in the right direction," he explained to Donna. "The question is: how did they know? How did they or why to do this? And where exactly are they?"

They both stood together, considering the bank of monitors in the security office of the powerplant. In one of the monitors, on the lower right, a fancily dressed young man could be clearly seen. Apparently, he was desperately fiddling with a control bank of some sort.

"I wonder who he is," Donna commented, moving to get a closer look.

"Who?" the Doctor asked absently.

"Him," she explained, pointing at the screen in question. The man moved, showing his face briefly. "Good looking, don't you think?"

The Doctor took a deep sniff, his eyes widening when the scent hit his Time Lord senses. "Is he? Can't say that I'd notice." He then glared at his companion. "You're not husband hunting again, are you?"

She merely scoffed at him. "As if. Anyway, he looks far too young for me."

"You shouldn't take age into consideration." He then lied, "But yes, he's not right for you."

It made him feel extra guilty when she sighed in resignation. "I suppose so. Not likely to get the interest of such a pretty toy boy, not with my luck. A drunk sailor feeling desperate during his first day ashore is about my limit."

"What's so appealing about him anyway?" he asked. "The pretty boy on the screen there, and not the…" His head bobbed to the side in order to dismiss the sailor image.

"Oh, I don't know," she nonchalantly answered. "There's something about him that attracts me. I can't explain why." She then nudged the Doctor's shoulder with her own. "And knowing my taste in men, he'd probably turn out to be on the other bus."

Or Time Lord, he didn't say, despite his confirmed suspicions. Instead, he pointed towards the entrance. "Here's your chance to find out. He's coming this way," the Doctor whispered in warning.

Seconds later a young man appeared in the doorway, flashing them a beautiful, sunny smile. "Hello. I'm the Doctor. You must be…" His countenance immediately fell and he gawped at Donna. "Donna Noble," he gasped.

"That's me," she confirmed defensively. "Did you see my name on a list or something?"

"No, but I know you were from somewhere, deep in my memory," he remarked, glancing meaningfully at the other Doctor. "It's nice to meet you and your husband," he cheekily added.

"We're not…," she started to deny, expecting her Doctor to join in in the usual way, but to her surprise, he didn't. "Hang on. Did you say you're the Doctor? Because you can't be," she accused.

The Fourteenth Doctor flashed her a heart-melting grin. "Yes, but you can call me Dr John Smith if you like."

"As do we," the Tenth Doctor replied, giving him a nod of recognition. Yes, he knew this young man was a different version of himself. One that he hadn't seen before and would have to remove his meeting from his memory later. "Thank you for your help."

"The Fiordorians are safe now," the future Doctor stated, "thanks to us."

There was something fishy going on between the two of them, Donna decided. As if they were pretending not to know each other. The mood had suddenly gone darker. "We're like the Three Musketeers," she joked.

"Anyway, we won't keep you," the Tenth Doctor began their farewells, cutting their meeting short. "Good luck in the future."

"And good luck to you both," the Fourteenth Doctor replied. "It was a pleasure to see you, but I must be going. Things to do, people to save. You know the sort of thing."

A quick salute later, the young Fourteenth Doctor ran from the room as though he was on a mission, leaving them on their own.

Donna peered knowingly at the Doctor. "I get the impression you know who he is, quite well."

"Erm." He gave his neck an anxious rub. "Not exactly. But I will, one day. Crossing my own timeline is always a tricky occurrence."

"So, there's another you, out there, running around, fixing things? Probably avoiding us right this minute."

"Yes."

"Blimey!" she exclaimed, blowing out her cheeks. "This time travelling certainly messes with your mind, doesn't it?"

"That's not the half of it, love." He reached out a hand to take. "Shall we go home?"

"Let's," she agreed, grasping his hand. "Onwards and upwards. Still… bit of a cheek, going around, pretending to be you."

"Don't worry. I'll deal with it in the future."