An alternate universe where Bones is an old country doctor, and Spock has run away from Vulcan to Old-West-Earth, and gets a job as a delivery man. Bones knows there's something up, but he can't quite put his finger on what.
The way the TOS characters slot in pretty much perfectly to the AU old west setting really highlights how much Roddenberry was influenced by westerns when he conceived Star Trek, not to mention the skill with which @captain-athos writes them.
Bones didn’t mourn the day Jamieson stopped showing up to make deliveries. As much as he needed the steady reliability of his various medicines and materials showing up on time, he did not particularly enjoy the inevitable interruption of the other man deciding that mid-consultation was a great time to stop for a lengthy chat. Bones had patients to see, and he got precious little time to himself during the day without having to worry about inane gossip from the next town over. So when Spock showed up one day instead of Jamieson and simply said “Doctor McCoy?” in a low, quiet voice, Bones counted his blessings.
When this exact exchange continued with no change, however, Bones started to worry. Was the man being impolite, when he simply nodded and left? Was it something about doctors in general? Or Bones himself? No, he didn’t hate the idea of being rid of Jamieson’s idiotic ramblings, but this was just as strange.
He said as much to Jim one night, during the weekly dinner they shared. As the Sheriff, Jim didn’t get much time to see his best friend anymore but nothing short of an emergency was going to stop him from making sure they had a moment, once a week.
“I’m pleased you’re so taken with him already,” said Jim with a grin, “he’s an odd sort but he seems nice enough. Talks like some sort of professor, though.”
“I wouldn’t know,” said Bones, pushing the food on his plate around with his fork. He didn’t have to look up, but he knew Jim would be watching him with that amused twinkle he got in his eyes sometimes, and the thought irritated him.
“I’m sure he’s just shy,” said Jim, “he keeps to himself, mostly. Hell, in between deliveries and running the telegraph office it’s amazing he has any time to talk at all.”