Sherlock's American accent was just as shit now, as it was when he first tried it out. The natural tones of his French ancestry made it next to impossible for him to erase the accent from his speech. The best he could do was fake a Southern accent, and hoped nobody from the South called him out on it.
It was more than keeping under the FBI's radar as Sherlock trapeze across the continental US. He learned very quickly that Sam and Dean had allies in nearly every state. It was obvious many of these allies held no love for them, but they were loyal nonetheless. Every single one of them were expert liars.
They were also expert marksmen, proficient in either Latin or Greek, and every single one of them hid a knife on their person. Sherlock began suspecting they were all part of a larger gang, like the Hell's Angels, but these men and women were not criminals. They acted more like bounty hunters.
Hunting what exactly? If Sherlock had more time he would investigate except the Winchesters bounced around the continent almost as easy as breathing. It irritated Sherlock when he got reports from Mycroft telling him Sam and Dean were seen in Nevada one day, then the next day they were seen in Maryland.
And it was only Sam and Dean. Not Castiel, and certainly not John.
In the past, Sherlock had chastised the American police for their inability to catch Sam and Dean. Both men were tall, handsome, and drove around in a black, 1967 Chevy Impala. It should've been quite easy to single them out, regardless of the massive landscape.
And yet, Sherlock found, despite all his abilities, he was having a hell of time tracking their movements. Mycroft wouldn't send him plain rumors. If the Winchesters were seen in Maryland, then they were in Maryland.
In a small hotel room in Oregon, Sherlock had taped to his wall a giant map of the United States. Pins of various colors dotted the landscape while strings connected them all. It took Sherlock only a day to figure out what the Winchesters were after in each state.
It wasn't money, or drugs, or weapons that motivated the Winchesters. There was always a pattern and it baffled Sherlock how none of the FBI picked up on this.
Sam and Dean never stayed in a city or town any longer than a day or two. Longer than that, then it was an indication for something else. And it was always death.
Sherlock read the police reports and newspapers. A healthy child would suddenly dropped dead the next day from heart failure. Cows are found mutilated. Husbands suddenly turn on their wives or a string of mothers suddenly drown their children.
The moment the Winchesters rolled into town, the odd deaths stop.
Yet there were contradictions. Sam and Dean don't leave each state with a clean conscious. There was always one last body left behind. Sometimes the body was found mutilated, head taken off, or burnt to a crisp. Other times there was no body, just a missing persons poster that's taken down a few months later.
Sherlock doesn't know what to make of this. John wasn't an idiot, despite how many times Sherlock called him that. The doctor's morals were unshakable and would not dare associate himself with murderers. But it seems no matter where the Winchesters went, a trial of bodies were found in their wake.
And if Sherlock was right in his estimate, over a hundred murders have been committed by them.
That shouldn't have sent a tingle up Sherlock's spine, but it did.
There had to be a safe house, Sherlock decided very early into his investigation. All serial killers had them. Even expert killers like the Winchesters would get antsy, wanting a place to lay low for a while and rest.
That was when Sherlock began methodically tracing the Winchester's route. The pins, the colored strings, all pointed to one small place in South Dakota.