He's human and she's a vampire. Makes sense; She's suffered from turning, she's cold and loveless but he wants to help her be a better person because he loves her unconditionally. Violence in her heart= nature of being a vampire, Beauty= She's even more beautiful on the inside than she is on the outside, Demons from her past= her murderous history from when she was first turned, Undisclosed desires= The desire between them aka love. (; just my thoughts.