Correspondence - Why is Harry desi?
I gave Harry Indian ancestry because it was something I'd seen in other places that I thought was cool, basically. I didn't flesh it out a lot in this particular fic, but I came back to the idea in The Head of the House of Slytherin, and Harry actually met his relatives in that one. I decided then that Harry's paternal grandparents would be Fleamont and Euphemia (sometimes people go with Charlus instead) and that Euphemia's mother would be Nandini Dearborn, nee Goswami.
A major reason I liked making Harry desi is that I really DISLIKE the idea that his parseltongue is a contamination from Voldemort. Snakes are animals. Parseltongue is a language. There's nothing inherently evil about it just because it's associated with a specific bloodline. I ALSO think it's stupid for parseltongue to be unique to Slytherins - though it's not weird for it to be a rare magical talent in a country with only two native snake species. "Salazar Slytherin" is so OBVIOUSLY not an Anglo-Saxon, or Norse, or Germanic name (especially compared to the others) that it made total sense to me for him to come from Southern Europe, where there ARE more snakes, and there was also a lot of intermixing in certain regions with 'Moors' - Muslims from North Africa and the Middle East, via the Islamic Empire. So that turned Slytherin from having a unique magical talent to having one that was fairly common in the region his family came from, but very unusual in the place he immigrated to.
I elaborate on this whole thing a bit more here: https://archiveofourown.org/works/17281838/chapters/69767415