Gail Carriger’s Parasol Protectorate series reminds me a lot of Jim Butcher’s Dresden Files. Not in the specifics, mind—they have some commonalities (vampires and werewolves as institutional powers, and a hero who deals with the supernatural on the regular), but also many, many differences (Carriger’s series is a romance-flavored thing, set in Victorian London).
No, the similarity that strikes me is how both series deepen the world-building as they go. Carriger’s first book is really a pretty standard supernatural romance, and there’s not much more to the setting than what’s needed to support that. But as the series go on, Carriger is forced to think about how her societies really work, and about what various characters’ backstories really are. So book by book, they evolve in subtle ways, never quite contradicting earlier books, but definitely taking advantage of the blank spaces present in the earlier ones to fill in an awful lot of stuff that wasn’t really lurking in the background then.
As it happens, this also goes hand-in-hand with her getting better as a writer. Soulless, the first book in the series, is kinda weak. The romance is super-tropey (hey look, two characters who hate each other at first sight, will they end up falling in love? okay, but what if he’s a gruff and uncommunicative alpha male, and she’s a free-spirited “spinster” in her twenties who thinks she’s unattractive because her breasts are too large and her complexion too Italian?), the supposed-to-be-witty banter mostly feels labored and unfunny, and the plotting relies on people being idiots in obvious ways.
Some of the plotting problems persist for a few books—there are scenes where people will narrowly avoid assassination attempts and then never mention it to people who really, really ought to know about it, and will take virtually no action as a result of it, because it’s not time to tug on that plot thread yet—but it gets better as it goes, and by the fifth book, that mostly doesn’t happen. The character and dialogue problems improve faster.
Still, even by the end, these aren’t much more than light fluff, with some serious flaws. They don’t seriously interrogate the underpinnings of their world—that all the characters are aristocrats in the service of the British imperial project isn’t really called out in any way whatsoever, for instance; and the idea of female political equality is openly mocked within the books in a way that I guess might be period-appropriate, but still seems a little weirdly off—especially given how aggressively independent the female characters in the book are. (The books do have a bunch of non-straight characters, though, so are good on that front.)
I enjoyed them enough to power through all five in a row, but I’ll only recommend them weakly: If this is the sort of thing you love, you’ll probably like these.