Trying to put together all the clues. Stan was cursed as a child, but he wasn’t in America at the time. Sam and Dean are both full sized and adults. Stan will not become part of the 221b gang, so probably not Sherlock. However, 1/3 of Torch’s ask was off, so I’m guessing that it was the “captured and sold to America” b/c he was cursed as a child and did meet the bros. So Sam and Dean are visiting England for some reason and happen to meet(read: grabby hands, bad Dean (or Sam?)) a wee Stan?