She is black on her mother's side, genetically speaking, but she never had dark skin. When elise showed up it finally canonised that marceline black as per her human half because elise is black I and many other poc knew marceline was black, well before fionna & cake confirmed it, but proving blackness without explicit author intent, especially for a character as beloved as her, is nigh.
Marceline/Analysis of Marceline's origin - The Adventure Time Wiki. Mathematical!
Adventure time producer adam muto spoke to polygon about the decision to portray marshall lee as a black character and the legacy of marceline the vampire queen.
Marceline abadeer, better known as marceline the vampire queen, is a fictional character in the american animated cartoon network television series adventure time and resulting franchise, created by pendleton ward.
She assumed the title vampire queen after having killed the previous vampire king prior to the start of the show.
