I came across this interesting article on ScreenRant
In short, it is this. Can a series about a younger Sherlock Holmes work without Watson? Will people accept it?
It's a tricky one. In plenty of pastiches, Watson has been replaced but, in my opinion, it rarely works unless the character is so similar to Watson that it may have well been Watson.
But this "rule" cannot apply when the stories are set before Holmes met Watson. If you contrive to crowbar Watson it, it'll will look as forced as it is. So, it does need to be someone else. But who?
It would need to be a totally original character. To be as close to the usual dynamic as possible, I feel it should be a medical student. Beyond that I have no real notion.
What do you think?