Vampire girl (age 22) x human girl (age 19). Vampire woman is an artist; she's looking for a muse (specifically a nude model, but she didn't put that in the listings). Human woman notices the listing, signs up, goes to meet the artist, becomes her muse (among other things) 
(I would want to be the human girl. Must be 3-4 lines, be prepared for minor smut, language, and seduction!!)