Like, what if Harry Potter had been a Harriet? Would the Dursleys still have treated her the same, or would Petunia have been happy to have a little girl to dress up? Would Dudley and his friends still have bullied her to the same degree? Would Snape still treat her with contempt or would he go all Petyr Baelish, and would Harriet fall for it? And how would Draco react differently? Would he be more or less aggressive?
Would Harriet still be as willing to stand up and fight, or would she have absorbed all the sexist bullshit about women not having valid opinions and just stay out of the way. Would Neville be the one to fulfill the prophecy after all? Or would the Order defeat Voldemort without any teenagers around? Or would Voldemort stay in power? Would she have still gone after Draco when he stole Neville’s remembrall? Would she wind up on the Quidditch team at all?
Would she be closer to Lavender and Parvati than Harry was with Seamus and Neville and Dean? Would she go to the Yule Ball with Ron after neither one can find a date? Would she and Hermione share beauty tips and help each other deal with their ridic hair? Would her patronus be a doe rather than a stag?
Would she still be attracted to girls, or would she be heterosexual? Would she fall for Cedric instead of Cho? Would she want the same things from a partner? Would she still end up with Ginny, or would she marry Ron after he spends pretty much their entire time at Hogwarts chasing her? Or maybe she’d get the Bad Boy thing and make out with Draco in Hogsmeade.
Or maybe Harriet would feel a complete disconnect to their assigned gender and choose to identify as something different. Would they work on presenting differently while living with the Dursleys and how would this affect their behaviour? Or would Harry wait until after Hogwarts to come out about this or not? How would this affect their romantic relationships? Would Ginny still be into a trans dude?
Changing a character’s assigned sex is so much more interesting and so much more complicated than the length of their hair and the stuff in their pants and whether or not they wear skirts