Romance series about a clan (?) of shifters, the head of which is a bear and he hires an assistant who turns out to be an untrained witch.

I remember that the FMC and MMC meet when she applies for a job as his assistant. He hires her and she’s immediately brought to his estate and told she has to stay inside her rooms after dark. Eventually she discovers that under the estate, there’s a shitload of vampires that are trapped under a spell or something but occasionally one escapes, which is why she has to stay locked up after dark. He then discovers that she’s descended from powerful witches, though poorly trained herself, so he has his friend train her. But OH NO TWIST, the friend is not a friend and tricks the FMC into releasing all the vampires, one of whom is the traitor’s twin sister. Also, they’re “fated mates.” I read this book like 4 years ago and I don’t remember a single character name. All the shifters turn into different animals. One is an alligator. That’s the plot of the first book.