Marceline is a half-demon and half-human vampire, She assumed the title "Vampire Queen" after having killed the previous Vampire King prior to the start of the show, Although she is over 1, 000 years old, she takes on the physical appearance of an 18- to 21-year-old, She is ethnically Black on her mother's side, but her skin is bone-white because of her father, a demon with pale blue skin., Having spent centuries traversing the Land of Ooo, she has evolved into a "fearless daredevil", and her fondness for mischief has turned her into something of a trickster., Consequently, in her first role, Marceline functions as the antagonist of the story, forcing Finn and Jake from their home. However, she eventually becomes their close friend once Finn recognizes that she is "a radical dame who likes to play games".