Author's note: I decided to try something new; a crossover. I know some people aren't fond of them, and I hope my regular readers won't be repelled by it or by my Supernatural story – but it'S fun.

I don't own anything, please review.

Sherlock Holmes never worried.

Or at least that was what he preferred people to believe.

Even after he had returned from the dead, he chose only to explain to a select few – John, Mrs. Hudson, Greg, Mike Stamford – what had happened. He simply didn't care what other people thought of him.

And he didn't care about other people.

He'd learned at an early age that caring was a disadvantage.

He didn't care. He wouldn't care. Mycroft had told Moriarty his life story, and while he understood why, he simply refused to –

Sherlock sighed and slowly put the sample he'd been studying away. He couldn't pretend anymore.

Sherlock Holmes was worried. About his brother of all people.

Mycroft had been acting –

If it had been anyone else, Sherlock would have thought he'd been acting "strange". But Mycroft didn't act strange. He was Mycroft Holmes, the British Government, and he always did what was best for the country.

Even if it meant betraying his brother.

Sherlock wasn't angry at Mycroft; he never had been. From a very early age, he had known that Mycroft only cared about his position and that he'd never be able to change that.

John had been angry; had refused to speak to Mycroft in the three years he'd been gone. But John was an emotional man; he would never understand his brother's reasoning. Just like he hadn't understood why Mycroft had simply accepted he was alive when Sherlock had let him know after a year, had just sent him the information he asked for and not demanded answers or wanted to know where he was.

John would never understand because he couldn't. His and Mycroft's relationship had always been complicated, to say the least. His brother was more intelligent than him – which he grudgingly accepted – but he was also, for lack of a better word, colder. He would never meet someone who would change him, like John had Sherlock; he would never give up his life for his friends. In a way, he was everything Sherlock wanted and yet dreaded to be.

Mycroft's betrayal had hurt, he wouldn't deny it. Although he'd never admitted it to someone other than John. Greg had grown to close to Mycroft since he'd left; he wouldn't risk their friendship. Mycroft would most likely scoff at his reasoning. He didn't care. It was strange enough that he was friends with Greg to begin with. Sherlock had decided not to question it. Mycroft had been alone, if not lonely (he doubted his brother would ever admit to feeling lonely) for a long time. He deserved a friend. Maybe, just maybe, Greg could be to him what John had been to Sherlock, even though the consulting detective doubted it.

Ever since he had returned and John had moved back into 221B, Mycroft had visited them sporadically, more often than not because he wanted Sherlock to take a case. But he had come when John was gone, or too tired to care, or when he'd known his visit would be very short. John was still angry and Mycroft had known it. When he hadn't been able to avoid seeing John, or rather John seeing him, he had always been polite and to the point.

He had cared that John was angry; he had cared that Sherlock cared that John was angry.

Not only that, but he had simply cared. He had cared about his country, he had perhaps even cared about Sherlock, he had cared about the memory of a little boy who'd run around the garden of a mansion, demanding he tell him everything he knew about pirates.

Not anymore.

When Mycroft had once again visited him and John and Sherlock could have sworn his eyes looked –

Empty. Almost black for a minute.

Not only that, but his voice had sounded – wrong, too. Mycroft had always been polite to a fault, calm, controlled. But he'd never sounded this flat.

And from this moment, he had known.

Something was wrong with his brother. And no one could convince him otherwise.

He hadn't talked to John about it. Yet. He knew he would eventually have to tell his best friend what was going on, but right now, he didn't have any proof that something was wrong with Mycroft, and the doctor would probably laugh if he suggested that believed him to be sick or at least not well because he was too cold.

He couldn't call Anthea, or however she chose to call herself this week either; Mycroft kept as close an eye on his employees, at least the important ones, as on Sherlock and his friends.

There was one other person he could call, though, one other person who was Mycroft's friend as well as his.

Greg picked up immediately, but, as Sherlock reminded himself, that didn't need to be a sign that he was worried. The DI was his friend, had been for longer than the consulting detective cared to admit to himself; naturally he would pick up the phone when he called.

Suddenly (and he was ashamed that he hadn't thought of it sooner) Sherlock realized that he couldn't say anything, at least not over the phone. Mycroft had access to every security camera in London, and he could lip-read. Furthermore, Sherlock was rather sure he had installed cameras in 221B too. He had found nothing when he'd searched the flat, and Mrs. Hudson had sworn that no pretend handyman had made it past her after his fake suicide, it was true, but this was Mycroft they were talking about. He had his eyes everywhere.

He had been blinded by sentiment; he couldn't just call Greg and expect Mycroft not to notice. He couldn't just call anyone and tell them that he was worried about his brother. He would know immediately.

So he said in his usual tone, "I don't suppose you have any cases for me? Interesting ones, I mean?"

He hoped Greg would notice the different wording. Normally he asked for "interesting cases" and didn't need another sentence to specify what he meant.

The DI sighed and he thought he'd failed to get his point across, when Greg answered, "You know I don't have anything for you" and emphasised the "anything" just a little too strongly.

And just like that Sherlock knew he'd been understood.

More than that, Greg apparently knew that they were being listened too or watched because he cleared his throat and asked, "Tell John to call me, will you? We haven't gone for a pint in ages" before he hung up.

Sherlock had to admit he was impressed. Greg knew that Mycroft had never stopped their surveillance, but that he likely wouldn't pay too much attention when he and John went to the pub, as was their custom.

It meant he was worried to. And he was the person who knew Mycroft best next to Sherlock.

Or rather, knew him as well as could be expected while not working for him.

Anyway, he quickly passed the message on to John with an expressive look. He knew his friend would understand that he needed him to meet Greg. The doctor just nodded and smiled, plus he briefly touched his shoulder on his way to the kitchen. He only ever did that when he realized Sherlock didn't want to give anything away for the cameras. Once more, he found himself thankful to have found a friend who understood him.

John left that very evening to meet Greg; Sherlock tried to concentrate on the experiment he was conducting, but this urgency of Greg's made him uneasy.

He couldn't shake the hope he was wrong, and he didn't want to; although he knew caring was a disadvantage, he had decided to care. Almost four years ago when he pretended to commit suicide. He couldn't act like he didn't care now; not only would John disbelieve him, but he'd learned that emotions were not only fascinating, but sometimes rewarding. He knew Mycroft had come to a different conclusion years ago, and he was aware why – their childhood had hardly been what one would call "good" – but nonetheless, he cared, and Mycroft wasn't acting like his usual pompous rather annoying self, like the brother he'd grown up with and had once been close to, and he wanted to know why. There had to be a reason. There was always a reason.

He didn't share his suspicions with John, yet he knew his doctor suspected something by the way he walked out of the flat; a brisk pace he only used when they were on a case.

He played his violin for several hours until John returned.

He was a little tipsy, but still managed to let him know – through a few almost invisible gestures while he was making tea that Sherlock had taught him soon after he'd moved in just to be sure they'd be able to communicate if they ever got captured – that they needed to talk.

So he let himself be persuaded that he should "help with the shopping for once" after they'd finished the tea the next morning, making sure he looked properly reluctant and followed John to the corner that was thankfully free of surveillance cameras; as long as they didn't stay too long, Mycroft wouldn't think they had discussed anything of importance.

"Greg is worried" John said once they were safely hidden from view. "He says Mycroft barely calls him anymore, and if he does and they do meet, he is withdrawn – even more than usual – barely talks – again, even more than usual – and doesn't seem to be interested in what he has to say in the slightest –"

"I understand" Sherlock interrupted him. He looked down at the floor, frowning.

"So Greg is of the same opinion".

"Yes" John replied, "and I would like to know what the opinion is, exactly".

Sherlock looked up and said, simply, "Something is wrong with Mycroft".

John shook his head. "I haven't noticed anything".

"You don't see him that often – and you wouldn't notice that he's become cold" Sherlock answered. There was no need to elaborate; they both knew John still had a problem with seeing the elder Holmes and that he wouldn't see anything wrong with the fact that Mycroft didn't greet him anymore.

John trusted Sherlock, though, so he simply nodded.

"Do you think he's ill?" he asked, and Sherlock bit his lip.

"I am not sure. He doesn't have a fever – at least he didn't the last time I saw him – and he doesn't appear to be in any pain or feel weak, either. I'm just – " he broke off, not sure how to describe it and John smiled.

"It's alright to be worried, Sherlock. You know him better than I do, and if you say something is wrong, I believe you".

Sherlock smiled back, silently thanking his friend.

"Sorry to interrupt your chick-flick moment" someone said behind Sherlock, "but are you Sherlock Holmes, by any chance?"

Sherlock turned around and took in the group standing before him.

Three men; Americans. The one who'd spoken was obviously the oldest and the brother of the tallest, who seemed to be sorry for the way his brother had introduced himself into their conversation; they'd flown in just a few hours ago and hadn't even had time to find a hotel.

They were... Sherlock frowned. Illegal weapons concealed in their jeans, the older one had a small bloodstain on his wrist – hit men? Hunters of some sort? – not enough data.

Behind these two stood another, smaller man (although still taller than John), in a tie and a trench coat, apparently content with letting the other one speak. Sherlock couldn't deduce him, just like he hadn't been able to read Irene Adler all those years ago; it was disquieting.

The younger one cleared his throat and Sherlock became aware that John had moved to stand beside him, hand ready to draw his own illegal weapon.

"Look –" the younger one started, "I don't know how to say this, but – you might have a demon problem."

Author's note: So, what do you think? I've never written something like this before.

And this takes place after season 8 of Supernatural, so Castiel is human.

Also, don't worry, not all my stories are going to have Supernatural in them now. I promise.