The Bloodbound Houses is a trilogy, and it is meant to be read in order. Each book ends on a door rather than a cliff, but the story is one long arc, and the pleasure of it is watching what the first book plants come due in the third.
The order
*One — Blood and Velvet.* A woman working nights in a New Orleans genetics lab runs a fourteenth-century sample against her own blood and gets a match. Everything she has been told about herself turns out to be a seven-hundred-year-old lie. Start here.
*Two — The Council of Knives.* She has a name now, and eleven days before the immortal Houses convene to decide what she is. This is the middle book, and it is where the world opens all the way out.
*Three — The Long Road Home.* The road runs east, to a drowned parish on the English coast and the thing the whole story has been walking toward. It also quietly opens the door to what comes next.
If you are new to gothic vampire romance
You do not need to have read anything else first. The Bloodbound Houses builds its own world from the ground up — the families, the rules, the cost of the gift — and explains it as it goes, through a narrator who is learning it herself.
What comes after
Two series grow out of this one: The Sablewood Novels and The Drowned Parish Novels. Both stand on their own, but both mean more if you have read the Bloodbound Houses first.