Disclaimer: I do not own "Doctor Who". If I did, Donna would have never had her memory wiped.
Rose could not believe what she was seeing. If her eyes were telling her the truth, then the TARDIS had just landed in her wedding. And if that was the TARDIS, the one she had known and traveled in, then that strange looking young man wearing the bowtie and tweed was, in fact, the Doctor.
It took her a moment to realize that she wasn't the only one there who saw it. People were going to want answers. She ran over to her parents.
"Mum, Dad," she said, "listen. Tell everyone to get to the reception hall. Start cocktails or whatever; just get them out of here."
"But what are we supposed to tell them?" Jackie asked, slightly hysterical.
"Tell them it's a trick," Rose offered. "Tell them that it's entertainment. Just tell them anything but the truth."
Jackie didn't look like she was getting it, but luckily, Pete caught on.
"Alright!" he announced. "I hope everyone enjoyed that bit of pre-reception entertainment. Now, if everyone could make their way to the reception hall, we can start making this wedding fun, eh?"
Many of the guests still had dubious looks on their faces, but they all soon filed out, leaving Rose, her Doctor, and the man she rather thought was the Doctor.
When everyone was gone, he decided that it was fine for him to step out of the TARDIS (she was sure it was the TARDIS, now).
He poked his head back into the police box. "Well, I know exactly where we are, now," he told Rory and Amy. "We're not in any sort of danger; well, you're not, at least. The only thing is that it's going to get rather confusing from here on in."
"When is it not?" Rory whispered to his wife. She chuckled. He did not care in the least about whether or not it was confusing outside of the TARDIS, he just didn't want to stay inside. It was rather spooky when it went completely dark, and it brought up some bad memories for him.
When they left the police box, they found themselves in a church facing two people who looked like they had just gotten married. They suddenly understood the Doctor's comment about something being very "familiar".
"Right, introductions," the Doctor said, clapping his hands together. He gestured to Amy and Rory. "These are my companions, the Ponds. That's Amy, and that's Rory. And they," he motioned to the other couple, "well, that's Rose Tyler, and that's, well, that's me. Not really me, of course. He's my metacrisis double made out of my hand and regeneration energy. It is a long story, believe me."
Neither Amy nor Rory understood that last part.
"So, it's really you?" Rose spoke up. She still couldn't believe it. "You regenerated again."
"Doctor, how does she know you?" Amy asked.
"To put it simply, Rose and I used to travel together," he answered.
Amy felt a little disappointed at that answer for some reason. She didn't know why. After all, the Doctor was hundreds of years old. Of course he would have had other companions before her. She guessed that she just didn't like the fact that he had never told her.
"I need to sit down," Rose said. She nearly fell onto a pew and put her head in her hand. Of all the people who showed up at her wedding, he was one she had never anticipated. And there was something worse.
"Wait a minute," her Doctor said, "if you're here, then you crossed universes. That shouldn't be possible. Not anymore, at least."
"I'm working on it," the Doctor admitted. "Hopefully, this doesn't mean that the universe is falling apart…Again."
"That does seem to happen a lot," Rose commented.
There was a long pause before the Doctor spoke again. "So, you two got married," he said, directing it to the newlywed couple. "Well, that's… anyway, what do they call you? I doubt anyone but Rose's family and Jake know you as 'The Doctor.'"
"John Smith," he replied. "Well, it's not like you weren't expecting that, right?"
Amy paused, remembering how the Doctor's Ganger had taken than name as well. How many times had he used it?
"Look, can someone just please explain what's going on?" Rory half-yelled. "You all seem to have everything figured out, but since we've been here, all Amy and I have gotten are some really confusing introductions."
This time, it was "John" who answered. "You two are his companions, right?" Amy and Rory both nodded. "So, you know what he is, correct? Well, when a Time Lord regenerates, he changes form."
The two knew that. Though they had never seen the Doctor regenerate, River had done it when she changed from Mels to her current form.
"Well, I'm a product of that," John continued. "Your Doctor used to look like me. There was some really complicated stuff with a hand, regeneration energy, and an extremely important woman that would take too long to explain, and I was created. I'm a perfect copy of him- well, the way he used to be, except I'm mostly human." He went onto explain that this was a universe parallel to their own and that they had been living there ever since the Doctor sealed off the universes.
"I guess that clears it up a bit," Rory said, though he really wasn't sure if it did.
"What I still don't get," Amy said, "is why we're here in the first place. You said that the Doctor sealed of the universes, which means it should be impossible for us to be here."
"Well, I've been here a few times before," the Doctor said. "The fact that it is impossible has never seemed to stop that, though I've never come here on purpose. The fact that we are here means that a very large hole was torn in the time vortex."
"And that's bad, right?" Rory asked.
"Very, very bad," the Doctor answered. "A large enough rip could very well cause the universe to collapse. It's not very easy to fix, and I need the TARDIS working again before I can do anything."
"Can't you just charge it up the way you did last time?" John asked.
"Of course, I can," the Doctor replied. "It just takes time."
"Well, in the meantime," John said, "you could, if you want to, come to the reception. You don't have to, of course."
"Brilliant!" The Doctor exclaimed. "I love weddings. Always go to weddings for the dancing."
"Please don't dance," Amy pleaded.
"What's wrong with my dancing?"
"You look like a complete dork!"
"What, he can't dance?" Rose asked, brightening a bit.
"I thought you used to travel with him," Amy laughed.
"He used to be able to dance."