A/N Here we are at the last chapter! I am so sad to see this fic end, I had such a good time writing it. Thank you for all of your support throughout this story, it means a lot. As always please point out any spelling mistakes and enjoy!

Big Brain Motel

Dean was shocked to see the glow of the TARDIS when he walked into the motel room. He had just been fussing over Sammy on the car ride back; he kept on insisting that he was fine, but he didn't look too good. Sam was pretty pale-he looked like he could barely keep his eyes open, and his head throbbed so much that being shot through the head seemed less painful. Dean had been holding him upright as they walked into the motel.

The TARDIS doors creaked open, "Ah there you are," The Doctor exclaimed, "I was wondering when you would get back."

Dean just stared at the Doctor, he seemed as cheerful as he was before the confrontation with the Laplji and demons.

"Laplji technology can have some pretty serious side effects. I just wanted to make sure Sam was okay." It seemed like a regular gesture any doctor would make, but Dean was still wary of the Doctor. The way he was able to scare off an entire alien race by only mentioning who he was sent shivers down his spine. Sure demons and monsters or anything of the like knew the Winchesters and were scared of them, but they didn't turn tail when the Impala rode into town.

Dean helped Sam walk towards his bed, Sam would have usually fought Dean's help but he was too exhausted to speak. That was not a good sign. Just as Dean got Sammy into bed Cas came through the door. He hesitated a bit seeing the TARDIS and the Doctor in the room but came in anyway.

"Ah Castiel," The Doctor exclaimed, "Can I have my sonic screwdriver back?"

Cas fumbled with his pockets pulling out the sonic, Dean looked up at Cas with a questioning look on his face. Cas was about to say something but the Doctor spoke first.

"Cas wanted to make sure I didn't take off. I wasn't going to anyway." Then the Doctor put his screwdriver back into his pocket and pulled out a stethoscope. He walked up to Sam, "I've got to check a few things to make sure the Laplji didn't leave you any surprises."

Sam was too tired to object and Dean didn't really know what to do either so he just let the Doctor do some doctor-looking things with some surprisingly mundane tools. Dean kind of expected them to be alien but maybe they were, at first Dean thought the Doctor was a weird British guy but he turned out to be an alien. But he didn't look like an alien, at least not until the confrontation with the Laplji. The Doctor's eyes had looked so old, much older than his body would suggest, and they looked so hollow, much hollower than his own or Sammy's. The Doctor must have seen a lot of crap, much, much more than they have, and the Winchesters were the kings of seeing crap. The only way the Winchesters got through it was because they had each other, but the Doctor didn't have anybody, how did he survive? Is that why he blew up a war because he got so fed up with everything?

The Doctor stood up, "Sam will be fine, just needs a good night's rest."

Dean looked at Sam only to discover that he was already asleep.

The Doctor only came back to make sure that Sam was okay, he was going to let Sam keep his book on the Laplji anyway. But he had to make sure when he came back that he had gotten back to his usual cheery self. He could usually flip a switch between his dark side and his light side, but today he just couldn't. But he also usually had Rose to talk his ear off when he needed it. He was better off without a companion, one less person he could put in danger. And after what happened with Rose, he couldn't do it again.

"I should be off then, places to be, people to save," The Doctor said walking towards his TARDIS.

"Hold on a sec," Dean said moving in front of the TARDIS, "Who exactly are you? And don't give me the tip of the iceberg crap, we know that already."

"I'm the Doctor, a Time Lord from Gallifrey and I've been time travelling for the better part of 900 years. Anything else you want to know?" The Doctor said trying to remain cheerful but it wasn't working.

"Y-you're 900 years old?" Dean asked a bit stunned.

"901 to be exact," The Doctor replied.

That certainly explained why his eyes looked so old Dean thought.

"Did you really blow up a war?" Cas asked, always blunt and to the point.

The Doctor sighed, "All you have to know is that I did what I did without choice," He said looking very sombre and voice growing colder.

"That's a load of bull," Dean practically shouted, "You always have a choice."

"And what would you choose," The Doctor said matching Dean's volume, "Destroy the two main parties of the war or let the war destroy the universe?"

"I'd find another way."

"There was no other way. Believe me, I tried everything I could think of to end the war. Nothing worked."

"You have a time machine, can't you go and stop the war before it began?"

"I can't."

"Why?"

"I just can't."

Dean stepped closer to the Doctor his hand reaching behind his back for his gun, "I'm only going to ask this one more time: Why?"

"It's a fixed point in time if I alter it then it would have catastrophic effects on the universe and the time stream."

"Fixed point in time, that's convenient."

"Time Lords have a sixth sense, we can sense what moments are fixed and what moments are in flux. This moment is in flux, you could let me go or you could shoot me with that gun you're hiding behind your back or we could break out into song and dance for all I know."

Dean was a little surprised that the Doctor knew he was reaching for his gun, but Dean knew the Doctor was hiding something, he could tell by the Doctor's voice. "You're hiding something."

"I'm sure you and your brother and your angel friend are hiding things as well. Forgive me if I don't want to talk about one of the worst days of my life. I'm sure you don't want to talk about yours."

The Doctor had gotten that last sentence right, Dean certainly didn't want to talk about the worst days in his life. "How do I know you won't blow up Earth?"

"You know how you and your brother travel across America to 'save people and hunt things'? Well, I do something similar, I travel across time and space, saving civilizations. Blowing up the Time War was the only way to save countless civilizations and the entire universe."

The room went silent, Dean seemed to be contemplating whether or not to let the Doctor go. The Doctor didn't sound like he was going to be another monster they would have to put in its place. Dean stepped aside allowing the Doctor to pass by and enter the TARDIS. Just as the door was about to close Dean spoke up, "Thanks for your help, we would have been dead without you."

The Doctor gave a small smile, it wasn't every day he got thanked. "Make sure you watch this next bit," The Doctor said as the doors shut. Then the TARDIS began to fade from assistance making the strangest wheezing noise.

"I was not expecting that," Dean said, he was expecting the TARDIS to suddenly disappear like the angels used to or to have some sort of rocket.

"Neither was I," Cas said in his usual monotone voice.

Dean sat on a chair by the table and began to think. He was happy that he let the Doctor go, in a way the universe needed him as much as America needed the Winchesters.

A/N Thank you again for reading this fic! It's the first one I have ever written so any feedback and pointers would be great! I am planning on writing some more crossover fics with some different T.V. shows! Also, do you think this has sequel potential? Let me know what other characters I should add. Stay tuned for more! Have a wonderful 2021! May you and your family and friends stay safe and healthy.