I saw a CFS (call for submissions) for short stories using Professor Moriarty as the MC (main character). It interested me, so I, of course, read the entire canon of Holmes stories again. For a figure who looms as large over the mythos as he does, Moriarty is strangely absent from the canon. It's maddening.
Moriarty is really only in one story - The Final Problem. He is mentioned in The Valley of Fear, but that's a bit of a cheat because 1) it was written after The Final Problem and 2) he's mentioned, but he's never shown. With so little to go on, it's difficult to flesh out the character enough to have a main character. There aren't many facts. There aren't even impressions. Just a sentence here or there.
The temptation is to resort to watching TV and movie adaptations, but that's problematic for several reasons. While Elementary gets points for originality in their portrayal, using a female Moriarty would be at odds with the original era. BBC's Sherlock... oh dear. While Andrew Scott's performance was amazing at times-- The scene where he asks the female cop to put a stick of gum in his mouth before they lead him into court is creepy and chilling. When he was at Kitty's apartment and walked in to find Holmes and Watson there, oh! You believed he was just some poor dupe.-- other times, such as the swimming pool scene where they first meet, was a bit too much. It was a unique interpretation, and one that no one should ever try to duplicate. The Jeremy Brett adaptations will probably define Sherlock Holmes for the next fifty years, but since they were so faithful to canon, again, Moriarty isn't shown much. I haven't seen the Russian adaptations although I hear that they were very well done. The only remaining modern adaptation that fleshed out Moriarty's role was The Game of Shadows, and I think that was the closest to my understanding of the character I've seen. However... they're rather brawny versions of these characters, quite in contrast to the Jeremy Brett! But the problem is that all of these are interpretations, and it seems wrong to use one of those to help form my vision. Only canon will do.
So I spent a week reading the canon. then moved on to gleaning information from the various online Sherlock Holmes fandoms. From there I was able to track down the most probable university where Moriarty was a professor, which fit in nicely with the two books he's said to have written. From there, I figured out the years he was mostly likely there, who were the (real) astronomers who would have been working at the observatory during those years, and their particular areas of interest. Moriarty wrote about asteroids Only one of the three probable astronomers he would have met did work with asteroids. That gives me an anchor year. I'm also researching a famous theft that happened around that time. Hopefully, these years overlap.
I'm collecting facts. But a list of facts does not a character make. I hope somewhere among all these notes that I find something to spark a personality. Being the anti-Holmes isn't enough.