The first volume in the Blood Bond Saga.

Vampire Dante Gabriel is starving. What he craves is red gold―human blood. After being held captive as a blood slave to a female vampire for years, he has finally escaped. Unchained at last, he follows his nose to the nearest blood bank to satisfy his hunger.
ER nurse Erin Hamilton expects just another busy night shift…until she finds a gorgeous stranger vandalizing the hospital blood bank. Though her logic tells her to turn him in, she’s pulled by stronger and unfamiliar emotions to protect the man who seems oddly infatuated with her scent. Chemistry sizzles between them, but Dante, plagued by nightmares of his time in captivity, fears he won’t be able to control himself…especially when he discovers a secret she doesn’t even know she’s hiding.
The connection between Erin and Dante grows, and she’s determined to figure out this strange man who seems drawn to her yet distant at the same time. When she pushes Dante for answers, he goes looking for them himself. What he finds could put Erin in mortal danger, with him as her only salvation.