Sometimes I racebend with fancasts to better differentiate characters in ensemble pieces (I once dropped a show bc I couldn’t remember which of three blonde women and two stoic vampire guys were which), and sometimes it’s because I think it will add an additional layer to a character or story.
Anyways I think Hexslinger’s Ed Morrow (and maybe Chess) should have been a person of color.
Okay some justification and why I think Ed Morrow could work as a biracial Chinese-American character.
The first book prioritizes the perspectives of three white (queer) men who are to varying degrees sexist and racist (especially Chess, the author's obvious favorite), with two of them being ex-Confederates, though the book sidesteps the idea of them being pro slavery. I can read about shitty characters but it's less comfortable when the narrative itself has a weird dissonance going on. I'm aware books 2 and 3 handle women and poc (especially women of color) better but that doesn't change the fact that in book 1 all the antagonistic characters are authority figures, women, and/or people of color, with a lot of the latter two. Making Ed a person of color doesn't fully solve issues this but I thinks adds interesting layer to the narrative and Ed, who is otherwise the least interesting of the initial trio (despite my fondness for him).
There were some Chinese immigrants in 1820 with the number greatly increasing with the California Gold Rush of 1848-55, most coming from the Guangdong province of southern China (due to famine and political unrest) and settling on the US West Coast. Book 1 is set in roughly 1866 and book 2 states Ed is 34, meaning he was born 1832. So he could feasibly be born between those two waves even if very few women immigrated (Afong Moy is the first confirmed in 1834) and it is more stretchy for him to grow up in a presumably mostly white town in the middle of Kansas as is canon.
Now you might wonder if being Asian-American (biracial or otherwise) would prevent him from joining the Union Army and becoming a respected Pinkerton but he totally could! Chinese-Americans fought on both sides of the Civil War and the Pinkerton Agency employed some women and minorities, primarily as spies.
In the case of Ed being biracial, the greater number of Chinese men immigrating meant that they would have to look for marriages outside their communities. Laws were passed to prevent Intermarriages with white citizens after 1850 and it was a widespread tabboo; even though Ed and any sibs would be born before these laws, their existence would be scandalous though some towns could be more accepting.
Thematically speaking, I think it would be fitting for Ed to be biracial and white-passing (as in actively attempting to 'pass' as white). This is a man who is both closeted with his bisexuality and so repressed about it that when Chess comes on to him, Ed first tries to justify his attraction and active desire to go to bed with him as just Hex magic that he can't fight so he might as well let it happen (at least in my interpretation, otherwise their fwbs deal starts with Chess magically drugging him into sex and manipulating him into staying). As a reminder, he is a Pinkerton Agent and a respected one, his boss is actively homophobic (though mostly just racist against Hexes), and overall considering how the setting and time period was, it makes sense for him to present as a white straight man when not in his home town. Something he can only set aside after going on the run with Chess and saving the world the world from a power-hungry Aztec goddess.
Also, I only have access to the sample on Amazon, but Eurasian: Mixed Identities in the United States, China, and Hong Kong, 1842–1943 by Emma Jinhua Teng seems like a good source and an interesting read in general (the first chapter goes into reactions to Chinese-Irish intermarriages in New York, which didn't come up in the sources above).