A/N: I haven't ever done a crossover before, and this is certainly one of the most challenging projects I've ever started. First of all, this is going to take place in several parts, called books, each with its own contained story. Like an episode. So this whole thing is like a season? I guess? Except not with twenty episodes. I can't do that. I also won't be updating every day like I've done with my other two Supernatural fics. School is starting soon, and I've got a publishing internship this semester. At most, I can promise a chapter a week. That much I can safely guarantee. But whether you get two or three chapters a week as well is debatable and depends on how much homework I have. :)

Disclaimer: I do not own the rights to Supernatural or Doctor Who.


Book One: Stranger

Dean really wasn't feeling very good at all.

Dad was out on a hunting trip, though, so Dean had to make the trip down to the grocery store on his own. He couldn't quite reach the top shelves with the strong stuff, but he could get some basic cold medicine and a nasal spray that worked when Sammy was sick, so hopefully it would work for him.

It was obvious to everyone in the store that he wasn't feeling good. His little hands reached out to grab every shelf as he passed by, and he could only breathe through his mouth. His whole head felt like it was going to explode, but he had to get in and out of the store fast; he'd left Sammy home alone, and he definitely wasn't supposed to do that.

But what was he supposed to do? He couldn't even sleep anymore because he kept waking up every fifteen minutes unable to breathe. And there were just some things that he couldn't put off until Dad got home. Besides, Sammy was asleep, so it wasn't like the kid could possibly get himself in any real danger.

And he'd only been gone for maybe ten minutes. He'd be back in no time.

Dean stumbled a little bit. He wasn't used to trying to get his balance like this. He was only eight, but already he was the best shot his dad had seen—his words exactly, and Dean was never going to forgot that—and he could handle himself in a fight. He was supposed to be good, Dad's little soldier. And so he hated being sick.

When he stumbled, he felt a hand behind his back, and a woman's voice said, "You okay there?"

Dean looked up. The voice wasn't American, and he wondered what this pretty lady was doing out here in the middle of nowhere. This definitely wasn't a popular tourist spot.

She was really pretty, actually. She had dark, smooth skin, and she had her hair pulled back so it was kind of spiky in the back. She was wearing a red leather jack, which Dean heartily approved of. And she had a really pretty smile. So, Dean tried to pull himself together and give her his best flirting smile. "I'm just fine, thanks," he tried to say, but the "thanks" came out as more of a "danks," so it was obvious he wasn't actually fine.

The woman crouched down in front of him and put her hand to his forehead. He would have tried to fight her off, but it was really all he could do at this point to keep himself standing, much less fight off someone who was obviously just trying to be too nice. "Doctor," the woman said quietly.

Oh, great. Dean hated doctors.

He tried to wave her off. "I'll be okay. I got medicine," he said.

The woman looked down at the stuff he had in his hands and shook her head. She knelt down and looked in his eyes, ears, nose, mouth. He would have tried to bite her for her troubles, but he needed to keep his mouth open so he could breathe, so that wasn't really an option. "That's not going to be any good. You haven't got a cold. I'll bet it's a sinus infection."

Dean frowned. He wasn't sure what the difference was, but he was quite sure that the second thing was harder to treat, and he didn't have the money for much more than what he was holding.

The woman seemed to understand his dilemma, and she took him under her arm. He wanted to protest, to pull against her, but he couldn't breathe, and he couldn't do much talking. And she didn't seem too bad, and Dean was pretty good at reading people. He didn't necessarily trust her, but he also wasn't going to use the gun he had tucked away in his little backpack.

"Doctor?" the woman called again.

A really tall guy poked his head out from behind one of the counters. He was carrying two jugs of milk—which was apparently why they were there in the first place. He had a huge, stupid grin on his face, and he looked over at the pretty lady with wide eyes. "Yeah?"

"I think we should help this young man get back home," the woman said.

"I can get home by myself. Lemme alone," Dean muttered. But there was really no stopping them anymore. The tall guy was grinning even more stupidly, and the pretty lady was checking his forehead for a temperature again.

The lady took the medicines gently out of his hands. "How much money did you bring, Doctor Smith?" she asked. (For some reason, when she called the doctor by his full name, she could not stop herself from smiling.)

The doctor person pulled out a bunch of bills from his pocket. "This enough, Doctor Jones?"

The lady rolled her eyes. "We should be fine," she said. She grabbed the stethoscope from around Doctor Smith's neck and listened to Dean breathing, just to finish her little checkup, then nodded as if she had already decided what Dean had and she was just finalizing the decision.

"Doctor Jones?" Dean repeated. He scrunched up his nose. She definitely didn't look old enough to be a doctor, and even if she was, Dean still didn't like doctors, no matter how pretty they were.

"That's me," the lady said. She motioned her other doctor friend over and held out her hand expectantly. Dean didn't know what she was doing, but the other doctor seemed to understand, and he put both jugs of milk in one hand so that he could dig around in his pockets. Finally, he found an old, tattered wallet and handed it to Martha.

"Come on," she said. "I know just what to get you." She paused. "You're not allergic to anything, are you?"

Dean shook his head.

Doctor Jones walked him up to the pharmaceutical counter. The lady behind the counter looked over at the two of them, and her lips pressed into a thin line. (Dean could tell what she was thinking; this lady wasn't his mother, so what was she doing there?)

"I'm Doctor Martha Jones," the lady said, handing over the tattered old wallet to the lady behind the counter. "This is one of my patients, and here's his prescription."

(Dean was confused. He had seen the wallet before, and it had a blank page in it. But when Doctor Jones handed it over, it had writing on it. How did that work? He hadn't seen her writing on it before.)

"That's a bit unusual, bringing him here yourself."

Dean frowned and opened his mouth to try and explain himself, but he could not get out more than a faint squeak before he realized he was going to have to sit down. Doctor Jones caught him and helped him to his seat, then smiled at the counter lady. "I have a soft spot for kids," she said, "especially when his parents don't care enough to notice when their son tries to self-medicate."

The lady behind the counter nodded her understanding, then went back into the pharmacy to get the things Doctor Jones had prescribed for him.

"Listen," Doctor Jones said as she crouched down in front of Dean, "can I trust you to read the labels right on the stuff I give you?"

"I'm not stupid."

"I never said you were," Doctor Jones said with a smile. She laughed when he pouted at her, which was exactly not the reaction he wanted. "I can tell you're a responsible kid if you're here on your own."

"I can take care of . . . ." He took a deep, rattling breath—it was hard to talk and concentrate on breathing at the same time. " . . . of myself."

"I'm sure you can." She gave him another big smile. "Where are your parents, anyway?"

Dean glared. That was the one question grown-ups were always asking him that he hated having to answer. They would always get so upset, like his dad was awful for leaving him on his own or some other nonsense like that. They didn't understand. His dad was a hero, and it wasn't his fault that his heroics meant sometimes he had to leave Dean in charge. Besides, Dean could handle it. "My dad's working," he said. "I gotta get home and take care of my brother."

Doctor Jones frowned. "You're home alone?"

Dean felt his fists clench. He hated that, hated when grown-ups acted like it was such a big deal. It really wasn't. He was very much fine with being alone because he knew how to take care of Sammy maybe even better than Dad did. And that was really all that mattered—taking care of Sammy. But now this grown-up doctor was taking Dean's precious time to give him a checkup and medicines he didn't really want, and what if Sammy woke up with nightmares and Dean wasn't there? He really needed to get back.

Doctor Smith came back to the pharmacy with a plastic bag in his hand with both jugs of milk inside. He looked over Dean, then Doctor Jones, then tilted his head at her in an unasked question.

"We're going to make sure he gets home safe, aren't we, Doctor Smith?" Doctor Jones asked, straightening Dean's collar for him. (Dean glared at her.)

"Of course," Doctor Smith said. He beamed at Dean. He also had a British accent, so maybe they were a couple? Dean frowned at them both, but then he had to turn away and sneeze, so they didn't get how annoyed he was with both of them trying to interfere in his life.

Finally, the lady behind the counter came back with some medicines, and Doctor Jones paid her and handed them to Dean as she ushered him towards the front door. "Now, make sure you take them only as often as the label—"

"I'm not stupid," Dean said. He snatched the bag out of her hands. "And I don't need your charity. How much did the medicine cost?"

Doctor Jones frowned down at him, but before she could say anything, the lights in the grocery store started to flicker.

Dean looked up and immediately went for his backpack. He stuffed the bag of medicine in the top pocket before he went for the main one. The whole place felt cold, and Dean knew exactly what that meant.

"That's not good," Doctor Jones said.

"No, it's very much not," said Doctor Smith. He fished some brown-rimmed glasses out of his pocket and stared around the dark before he looked down at Dean again and realized that the eight-year-old was holding a gun. "Oh, now, that's even worse. Where did you get that?" Doctor Smith asked, wrinkling his nose and looking at the gun like it was the enemy and not whatever was making the lights flicker.

"Shut up. Me and my dad handle this kind of stuff all the time," Dean said. He tried to sound braver than he felt, not only because he was sick and sounded weak anyway, but because he hadn't really ever fought anything without Dad.

"Don't you want to see what it is first before you go shooting it?" Doctor Smith asked. He held out his hand to try and take the gun from Dean, but Dean was having none of that.

"Shoot first, ask questions later. Otherwise, you end up dead," Dean said. He kept a firm grip on the gun, but by then, the crisis had passed. The lights were restored, and the cold went away.

"Ah, see, there. That's better," Doctor Smith said, with still one eye on Dean and the gun.

Carefully, slowly, Dean put the gun back in his bag. "Says you," he muttered. It had been his experience that when things went away, it was usually because they'd gotten what they wanted.

Doctor Smith stared long and hard at Dean before he turned back to Doctor Jones. "You know something, Martha. I think our grocery trip just got extended," he said.