"You're kidding," Molly said, mouth agape, "A demon is after Sherlock?"
"Yes," Castiel said, his expression serious, "A very powerful demon."
"Do you know who he is?" Dean asked.
"I do not," Castiel replied, shaking his head slowly, "but from what I've seen so far, this particular demon enjoys messing with a person's head before possessing them, weakening their defenses to the point where they welcome him in, rather than simply taking them by force."
"So, what? We've got a demon that likes to play with its food?" Sam asked, confused.
"No. Demons don't eat people," Castiel replied before turning to Sherlock. "You need to ward your home and stay in it. Sam and Dean will help you with the sigils, but you have to promise not to leave."
"You're all insane," Sherlock said, looking at the trio like they were bizarre otherworldly creatures.
Sam sighed and Dean rolled his eyes.
"Look dude," Dean said, annoyed, "I don't care if you believe it was a hellhound or not, but something killed this man and it will kill you and your friends if you do not go home and ward yourself against it."
"Better safe than sorry," Sam added helpfully.
"The only thing I am in danger of is my brother's nosiness. I refuse to indulge this lunacy any longer," Sherlock said, turning on his heel and walking to the door with a swish of his coat.
"Sherlock wait!" Molly called out. Sherlock turned around huffily and glowered at her.
"What, Molly?"
"I think we should give them a chance. I mean, it would explain a lot. I've been getting bodies like this for a couple weeks now and I still have no explanation save for this one. Not to mention each one has been found closer and closer to Baker Street. I'm getting worried, Sherlock. I don't want to see you get hurt," Molly said, fiddling nervously with one of the buttons on her lab coat.
Sherlock's gaze softened slightly.
"But Molly…" he began.
"No, Sherlock," Molly interrupted, "I'm starting to believe them, if for no other reason than the fact that Castiel here literally appeared out of thin air two minutes ago. Do not even try to dispute that. I saw it with my own eyes and you know I wouldn't lie to you."
Sherlock appeared as if he was going to argue, but decided against it. He turned back to Castiel and the brothers with an icy glare.
"Fine. What do you need?" he said reluctantly.
"We'll need red spray paint, salt, and holy water," Sam said, counting the items off on his fingers. Dean grinned.
"All right! Let's gank this demon!" he said, draping his arm over Sherlock's shoulders and practically dragging him out of the morgue with Sam close at their heels. Molly started to follow them, but Castiel called her back.
"Molly," he said solemnly, "Watch him. He trusts you more than anyone. You'll likely be the only one that will actually be able to get through to him."
"I don't know about that, but I'll do my best to keep him safe," Molly replied meekly.
Castiel and Molly joined the boys outside of Bart's. Sherlock hailed a cab and ushered Sam, Dean, and Castiel inside.
"Molly and I will take a separate cab. Do not, under any circumstances, go inside my flat until we arrive. Do you understand?" he said, piercing each of the Americans with a look cold enough to freeze over Hell.
"We got it, Curly," Dean replied, winking at Sherlock, "Don't worry, we promise we won't get hamburger grease and ketchup all over the precious Britishness of your little 'flat'."
Sherlock bristled at the elder Winchester's words and slammed the door of the cab. He gave the cabbie directions to Baker Street, and the little black car drove off into the busy streets of London. Molly watched quietly as Sherlock hailed another cab for the two of them, trying to determine what the eccentric detective was thinking. The cab rolled to a slow stop and Sherlock chivalrously held open the door for Molly, much to her surprise. She slid in and moved to the far end of the back seat, and Sherlock followed close behind.
"221B Baker Street," he said curtly, and flipped up the collar of his Belstaff. Molly giggled, and Sherlock looked over at her quizzically.
"Why are you laughing?" he asked warily, unsure if he had said or done something wrong.
"It's silly, that's all," Molly replied, smiling at him.
"What do you mean?"
"You flipping up your collar like that all sulkily."
"What are you talking about? I don't do that," Sherlock said, blushing slightly and remembering a similar conversation with John that had taken place three years earlier.
"You most definitely do," Molly replied, "But really Sherlock, you don't need to brood and freak out internally. I'm not sure if what the Winchesters are saying is true, but even if it is, shouldn't you be excited to learn something new about the world? A discovery such as this doesn't mean that everything you know about the world is wrong, it just means you don't know everything yet. As a scientist, you should be elated."
Sherlock stared at her, taken aback. An odd look that Molly couldn't quite place flashed across his eyes for a fleeting moment. He turned away and looked out the window, watching nothing in particular as he immersed himself deep in thought. Molly, knowing she would never be able to get through to him in such a state, cast her eyes about the cab and took in all the strange little details. The back seat was relatively clean, only a single stray gum wrapper was lying lonely by the door. An odd brown stain from something she decided she definitely didn't want to know about stretched across a rather large portion of the roof. There was a little red tassel hanging from the rear-view mirror, and the bells on it jingled softly whenever the cab hit a dip in the road. Molly decided that she quite liked this cab and settled back further into her seat, thinking about everything and nothing.
Before long, however, her train of thought led her back to the Winchester brothers. Molly furrowed her brow, worriedly. She wondered what it would mean for her and Sherlock if this so-called demon was real. She toyed with the ends of her hair and ended up examining her fingernails. She used to have a bad habit of biting her nails a few years back, and the urge to take it up again was surprisingly strong at the moment. Molly brought her hands back to her lap and looked over at the brooding detective seated next to her. She had a feeling that if Sam and Dean were right, Sherlock would have a major existential crisis and mental breakdown at the same time. Molly sighed. A large part of her hoped that the Winchesters were just crazy, but she still had a sneaking suspicion that they were perfectly sane, and there really was something truly evil targeting Sherlock.