Hiya!
Recently I watched the series 4 finale. Then I browsed youtube and saw the deleted scene where the Doctor gives his duplicate a TARDIS seed. So it gave me this idea.
Oh, and, of course, I don't own any of these characters.
The Doctor was walking the streets of Cardiff as if nothing was wrong. Because, really, nothing was wrong. He was with Amy, Rory and the lovely River Song. For the first time in a very long time, they were not chasing daleks, oods, cybermen, cracks in walls... they were just walking around town. No investigating just a very odd double date.
Amy and Rory walked hand in hand, hanging back from their daughter and their son in law. It was awkward enough just having to talk about it, they didn't want to take part in the actual dates. The Doctor and River had no real objection to this arrangement. They weren't much happier with the awkward conversations they had.
Suddenly, The Doctor pulled River to the side and they hid around the corner of a building. Amy and Rory gave him a weird. The Doctor tried to sign them an explanation. When that didn't work, River just motioned them to hide with them.
"Doctor, can I know what's going on now?" Amy asked when she approached him.
"If you look over there" the Doctor whispered "You will see the past me." The other three tried to turn the corner to take a peak. "No don't look! He'll see you!" the Doctor hissed.
"Why can't we say hello?" Rory asked.
"Because he can't interfere with his timeline" River said. "That's a very young version of you..."
"What makes you say that?"
"You're with Rose."
"So I am. That's not that young!"
"Wait, sorry, whose Rose?" Rory asked.
"She's an old friend of mine" the Doctor said.
"Well, let's go say hello!" Amy said.
"I can't" The Doctor said. "Time line. Paradox!"
"You can't... but we can. Come on Rory! We can find out what the Doctor was like when he was younger!"
"No!" the Doctor reached out to grab them but it was too late. By then, the two had already pranced off into the distance to meet the tenth incarnation of him.
"Doctor, it's not so bad. So what if they say hello. That's all they'll do. Say hello" River said. The Doctor looked around the corner to see the confrontation. Then he turned back to River.
"You want to hear something weird?"
"Always."
"I don't remember this..."
"What do you mean?"
"They're interfering with my timeline. That should alter my memories, but it's not. I don't remember meeting a red head and her husband in Cardiff. Another thing, I've ben very careful about my timeline. I've made sure to never to cross it unless absolutely necessary. I've never come to this date."
"Well, you must have. How else could you explain seeing yourself right there talking to Amy and Rory?"
"A parallel world and a duplicate..."
"What?" But there was no point in questioning him. By then, he was already running towards himself. River groaned and followed the Doctor.
"Amy, Rory! Hello!" the Doctor said wrapping his arms around them. Amy and Rory exchanged confused looks. "Rose, haven't seen you in a while. In a very long while. How are things? How's Jackie? Does she still hate us?"
"I'm sorry, who are you?" Tenth Doctor asked.
"And what do you mean us?" Rose asked.
"Us. Me, and you" The Eleventh Doctor gestured to the Tenth Doctor. The Tenth Doctor's jaw dropped in excitement.
"No! That's incredible! I live! That's great news!" Tenth Doctor said.
"Doctor, an explanation please..." Rose said.
"Doctor, whatever happened to interfering with your timeline?" Amy asked.
"Oh, that's the beautiful part. That's not me. Well, he is me. But not really. He's part Time Lord part Human! All the memories of my past" Eleventh Doctor said.
"I think a very large explanation is in order right now..." Rory said.
"Well, we have all the time in the universe! Let's catch up, shall we?" Tenth Doctor asked.
"Yes! So many questions for you! Should we go to a cafe and eat some fish and chips?" the two Doctor's looked at Rose and smiled.
"Alright. Come on, Doctors. Let's go" River said pulling them along with her. The rest of the companions closely followed them.
They all walked together. The Doctors leading the way and the companions following them speechless. The Doctors were deep into conversation, laughing and reminiscing. The companions would occasionally exchange the awkward glance, but that was it. Finally they arrived at a fish and chip restaurant and they all sat down together.
"So, me" the Eleventh Doctor said with a smile. "This is Amy and Rory." They shook hands and exchanged a smile. "and I'm sure you've already met River Song."
"Professor River Song?" The Tenth Doctor asked.
"Shhh!" the Eleventh Doctor cut him off. "Spoilers." The Tenth Doctor smiled.
"So at this point we know more about her than she knows about us?" he asked.
"Well, I do..." the Eleventh Doctor said.
"Aren't you forgetting someone?" Rose asked bitterly.
"Oh, yes! Amy, Rory, River, this is Rose. My old friend-"
"Friend? Is that it? Is that all I am to you now?" Rose hissed.
"Rose, come on" the Tenth Doctor whispered to her. "You knew things would be different now." Eleventh Doctor and River exchanged a look.
"Let's talk about something else" River said quickly.
"Yes. Sounds good" the Tenth Doctor said. Rose didn't say anything. She just looked at the Eleventh Doctor bitterly. "How about you tell me how you're still alive?" the companions stared at the Eleventh Doctor in shock.
"What are you talking about?" he asked.
"Last time I saw you, the Ood had said that your song was ending... that you were supposed to die."
"Oh, yes! They did say that. That my song would end with four knocks." The Tenth Doctor gasped.
"Master!"
"You'd think. But no. It was Wilfred."
"How?"
"Radiation chamber. Knocked four times to get my attention. I absorbed the radiation saving him and then regenerated saving myself."
"But you were supposed to die..."
"If I had died every time I was supposed to die, you wouldn't be here."
"That is true."
"So, now it's your turn" Eleventh Doctor said. "Why don't you tell me how you are here."
"Oh! Right! Well, you see... in our world, we were invaded by Cybermen-"
"Cybermen?" Amy asked. "What are... Cybermen?"
"They are a race of cyber technology that believe that all humans should be upgraded" Rose hissed.
"Okay" The Eleventh Doctor said. "And how did that lead to your arrival here?"
"Well" the Tenth Doctor started. "you see, they were trying to upgrade all the humans. And I, of course, had this very clever, very complicated way of getting rid of them. And it nearly worked too only... well, you know how they always try to convert us into their cyber leader? We were never compatible. As it turns out, now that I'm human, I'm very compatible. In fact, now that I'm human, I'm just perfect to be their leader."
"I think I understood some of those words..." Amy said.
"So, then I had to find a way out. So Rose and I went into the TARDIS-"
"The TARDIS?" River said. "How can you have a TARDIS? He flew off with it when he left you guys in the parallel universe."
"Yes, he did, but he also left me with a TARDIS seed. So I was able to grow one quickly without any problems" The Tenth Doctor said.
"But that doesn't explain how you got here" the Eleventh Doctor said.
"Well, I can't really explain it. Last year there were these... cracks in time and space. Those had created a hole – a gateway – between the parallel universe and this one. So, we took it as a chance to get out-"
"You mean you chose to escape?" River said.
"I wouldn't go as far to say that-"
"YOU WILL BE LIKE US. OR WYOU WILL BE DELETED!" All six of them stood up and stared outside to the streets. Crowds of people were running away from the metal men.
"You IDIOT!" The Eleventh Doctor screamed. "Do you realize what you've done?" the Tenth Doctor stared wide eyed at the danger that awaited them.
"Doctor, what's going on?" Amy asked
"In your cowardice you led them STRAIGHT TO US!" Eleventh Doctor said, ignoring Amy.
The Cybermen marched through the streets as men, women, children ran away screaming.
"I... I didn't realize..."
"Doctor, we need to get out of here-" River said.
"And leave everyone to suffer? Please! We're going to save this world and then we're getting these two home and then we're closing that hole for good!"
"Um... Doctor..." Rory said pointing behind him.
Everyone turned towards the direction he was pointing at. To everyone's horror a cyberman had spotted them. He was marching towards them, destroying everything that stood in its way. It broke down the doors of the little fish and chips store and marched towards them.
"YOU WILL BE LIKE US. OR YOU WILL BE DELETED."
"Yeah, let me tell you something. There's not a very high chance of either of those things happening today" Eleventh Doctor said. The cyberman stared at the Doctor.
"YOU WILL BE OUR LEADER-"
"Yeah... try again, big guy. Not compatible. Remember?"
"THEN YOU WILL BE DELETED!" The cyberman touched the Doctor and set a wave of electric currents through his body. The Eleventh Doctor collapsed backwards. Rory and the Tenth Doctor barely caught him. They all looked at the cyberman who was inching closer and closer towards them.
"DELETE! DELETE! DELETE!"