First in the Blood Ties series by Jennifer Armintrout...
As if it isn't obvious from the title of both the book and the series... vampire book! So as is traditional, vamp rules... no sunlight, but able to be conscious during the daytime, can eat regular food it just doesn't do anything for them, they need blood to sustain them. Holy water will burn, staking works, or severe injury beyond their ability to regenerate (which gets stronger the older they get). They transform somewhat when feeding or if there's strong emotions going on. There's also a strong tie between sire and offspring. There's also this odd thing with an extra heart that grows allowing the human heart to be removed but it's still somehow attached to the vamp and if it gets staked they die.
The interesting bit is that there's a group of vamps that want to prevent any more vampires from being created. They have a long list of rules that they expect everyone to follow and if they don't... well, the consequences are rather severe! Things like no creating vampires, no feeding from unwilling "donors", no hurting humans, and if another vampire is going to die they have to let it happen. Even if it's a "good" vamp or a friend, kind of like a DNR order, no extrordinary measures!
So, our main character is a doctor in an ER and ends up being accidentally turned by a vampire that was brought in to the hospital. He's a bad guy so she's automatically marked for death by this vamp group because the tie between them will make her do what he wants. Of course she's not a fan of this plan and wants another option.
A "good" vamp does end up helping her and manages to get himself in some serious trouble along the way, both with a witch and with the vampire group (for whom he works) since he's breaking the rules.