One of Notte’s currently living eight “first-born” children – that is, a vampire he made himself. She was made approximately 500 AD.
Notte chose her because of her skill with the harp. Not unlike Salome (not first-born, though hand-picked by Notte), Elise’s talent eclipsed ordinary musicality by such a degree that he could not let her simply age and die and be lost to the world.
Elise is a little vain, but perhaps deserves to be; she was a primary influence in Dante Gabriel Rosetti’s style.