I don’t know of anything that is extremely simular to Demon Accords… Other series has some elements. A vampire run night club, strip joint or bar is a very common one.
For me it isn’t the supernatual elements or that there is an extra ordinary secret world or that there overpowered defenders of the world but how author eases you into the world and where the story will go is very hard to predict yet fits logically in universe that has been built. Every book for the most part has been a surprise and a delight and has the world expands to a cast of thousands how characters show up from books past. Demon Accords and Zone War are my current favorate reads.
One series that does share a underground world that is being forced to the light of day. Is Patrica Briggs, Mercy Thompson series. up to 14 books this comming may 7.
“Mercedes is a Volkswagen mechanic living in the Tri-Cities area of Washington. Her Native American heritage has gifted her with the ability
to take the form of a coyote at will. She’s surrounded by far more powerful supernatural beings, including werewolves, vampires and an
assortment of fae.”
Each book in this series is a whole story with a beginning and an ending, however the plot of each book relies heavily on the prior books in
the series. It is recommended that you read the full length novels in the order they were published.
Another series… you might find interesting is the Elfhome series by Wen Spencer
Inventor, girl genius, Tinker lives in a near-future Pittsburgh which now exists mostly in the land of the elves.
She runs her salvage business, pays her taxes, and tries to keep the local ambient level of magic down with gadgets
of her own design. When a pack of wargs chase an Elven noble into her scrap yard, life as she knows it takes a serious
detour. Tinker finds herself taking on the Elven court, the NSA, the Elven Interdimensional Agency,
I hope you find these helpful.