Fallen (The Transformed Prequel). The Transformed

Samantha Erikson is a vampire with one mission: to rule the immortal world.  And she's almost there. Just when everything is going according to plan, she gets sidetracked with the assignment of pretending to be a high school student in a small town. It's humiliating enough to go from stilettos to sneakers, but Samantha must also follow the most boring person alive: the teenage girl who stands between her and the throne.  When she has had all she can take, she finds a fun distraction: a football player who isn't scared of her kind.
There's one problem. Against her better judgment, she falls in love with him. Now she must decide between the mortal she adores and a place of power in the supernatural world. If she tries to have both, she could lose everything. This is the prequel to the Transformed series - it can be read on its own or in addition to the main series. (This novel was formerly two separate novellas: Fallen & Taken.)