Sherlock Holmes and the Watchmaker of Filigree Street are both set in London in the 1880s, please steal my crossover fic ideas
Option 1: Mori and Thaniel meet Arthur Conan Doyle. Mori says something cryptic like what he tells Dolly Williamson at the end of Watchmaker ("You think you're dying, but you aren't. You need to eat some proper fruit and go to the sea"):
ACD: how could you POSSIBLY know this secret fact about me
Mori: I.....deduced it from context clues
Thaniel, internally: Keita no one is going to believe that you can just DEDUCE something like that
ACD: how absolutely fascinating, tell me more
Thaniel, internally: screaming
Option 2: Post-Watchmaker, Mori and Thaniel meet Holmes and Watson. The opportunities are truly endless but here are some ideas:
The four of them are somehow connected to the same case. They meet and Holmes and Mori start arguing very politely and very stubbornly. Thaniel and Watson inadvertently exchange the exact same long-suffering glance. Each spends the rest of the meeting absolutely terrified that the other has discovered their Big Secret
During the case, Mori sets up a convoluted plot to get Holmes to overhear Thaniel playing piano. Holmes and Thaniel's budding musical friendship is almost ruined when Holmes discovers that Thaniel actually WORKS FOR Gilbert and Sullivan, those uncultured crowd-pleasers who are ruining the London music scene
Thaniel pulls Watson aside. Excuse me, is Mr. Holmes, er, you know...? Watson: I'm not SURE what you're trying to IMPLY. Thaniel: I meant is he also a [whispers] clairvoyant? Watson, sweating bullets: no he's not a clairvoyant, what an absurd thought, he's just really fucking good at his job, hahaha next question.
At the end of the case: Holmes: so, Mr. Steepleton, I see that you and Baron Mori adopted a child to help with your work, she seems marvelous. Watson: do NOT get any ideas
Option 3: Before Thaniel and Grace's marriage, Grace decides to bring The Case Of The Potential Clairvoyant (And Is My Fiancé In Love With Him Or What) to that detective she read about in the newspaper
Holmes: ah yes, he's in my notes as "Baron Mori, that asshole who is somehow connected to a lot of shit I can't prove." Grace: this feels right
Holmes thinks Grace must be joking when she says she's a chemist, because Women Can't Be Real Scientists. He tests her by saying something condescending and complicated that he thinks will go over her head. She replies with "oh, I just read an interesting monograph on that reaction, but the experiment's design clearly had some fatal flaws." Holmes reevaluates everything he thinks about Grace in 15 seconds. What if he showed her that current experiment on sulfer dioxide...Half an hour later, Watson kicks Grace out of Baker Street before she and Holmes blow something up.
Holmes meets Matsumoto and hates him on sight. That afternoon, to Grace: "Why are you getting married again? You're both obviously in love with other people, this seems avoidable. Also, your future husband is beyond irritating but he seems to genuinely care for you." Grace: excuse me. you dare. you presume.
"So as far as I can tell, Mori hasn't committed a crime, but I did uncover this plot to assassinate a prominent Japanese minister." "But does Mori have something to do with it?" "Probably."
