The Doctor firmly grasped the controls of the TARDIS and breathed in a sigh of relief, another civilization that was saved from The Daleks. He started the take off sequence when something went wrong. There was another viechle in the Time Stream, not a TARDIS, it was too small and his technology would've picked it up on the spot. He had no time to react before a DeLorean materialized within the TARDIS console room.

"Yes, can I help you?", The Doctor asked.

Immediately a human male teenager wearing jeans, a life reserver and a plad shirt opened up the door.

"Doc! Where are we?"
"I'm sorry, there's a mistake, I'm not 'Doc' I'm The Doctor"

An older man with wild frizzy hair walked out wearing a brown coat, a red shirt and brown pants.

"Great Scott!"
"Look, do you mind if I explain something."
"Who are you?"
"As I told your young friend over there, I'm The Doctor"
"Where are we Doctor?"
"In the TARDIS. Its a sort of...well, Time Machine."
"Great Scott! We must have merged in a sort of Time Vortex that has...no point in time."
"Actually it does, its just human beings can't quite grasp it yet."
"Human beings?" Marty asked, finally joining in
"Oh, thats not important, what IS important is that you have your hands on a Time Machine that was built by a human", The Doctor said, "what makes that particularly interesting is that it looks like you come about 300 years too early before Time Machines became available to anyone other than Gallifreyans."
"It was what I've been working on for 30 years!", Doc Brown said worried "I didn't know!"
"Don't panic", The Doctor said "It should be easy enough for you to go back to your main time...where were you trying to get to, anyway?"
"Wednesday October 21st 2015!", Doc Brown said, "We need to fix Marty's future. His kids could be in danger. Look, Doctor...I'm sorry, I never got your name"
"I apologise my dear fellow", The Doctor replied, "I never tell anyone my real name."
"Okay, Doctor, can you fix my DeLorean? I don't know what went wrong this time."
"Say no more", The Doctor said, springing into action "If I don't, the whole of creation could be destroyed and that could prove to be very nasty."
"Great Scott!"

The Doctor ran to the DeLorean and pulled out a large Sonic Screwdriver and started messing around with it.

"Oh this is your Time Machine", The Doctor said, "I don't like it"

Marty walked over to his lifelong friend and started chatting.

"Doc...who is this?"
"If he says he can fix the DeLorean, I trust him. His scientific mind could rival ALL my idols, Newton, Edison..."
"Edison stole most of his ideas from Nikolai Tesla!", The Doctor yelled from the DeLorean, still working on it.
Emmett Brown looked over at the man who was changing his lifes work, wondering what this would bring for his idea of Time Travel.

"There we are", The Doctor said "You should be ready to go to 2015. I also changed the Time Circuts, if they start blinking to October 21st 1885, don't worry. Its just a glitch. Also, your Time Machine may have experienced ice over it the first few times it went through time, thats because it needed a temperature stabilizer that could get it through the Time Vortex safely."
"Thank you so much, Doctor" Emmett Brown said enthusiastically, "I'll never forget this"
"Well its only a matter of...wait a minute, did you say your going to alter your friend's future?"
"Yes", Doctor Brown said.
"Okay, I hope you enjoy it", The Doctor replied

Marty looked over at his friend, worried.

"You've already done this, haven't you?", The Doctor said.
"I kind of, sort of, changed the way my parents met and...The Doc here met me 30 years before my original meeting with him.", Marty said worried.
"That would mean your part of an alternate reality" The Doctor said, "I can try and fix it to the way it was. But for now, enjoy yourselves."

The DeLorean powered up and went through the open doors of the TARDIS as Doc Brown and Marty waved back. The Doctor closed the doors of the TARDIS and materialised to find himself somewhere, he didn't know where...and thats how he liked it.