Maruca is Biana's ex-friend. Little is known about Maruca, except that she is Wylie's second cousin and she is currently Stina's friend. After Biana began hanging out with Sophie in Book 1: Keeper of the Lost Cities, she spills a lot of Biana's secrets to Stina, like how at first Alden told Biana that she had to be friends with Sophie so Sophie would come over more and Alden could keep a better watch on her (which causes Sophie to be sad and she wanted to be alone, resulting in her kidnapping). This is why Biana no longer wanted to be her friend, because she spilled her secrets and was mean to her friends. Maruca interacted with Wylie often as a young child.
Maruca has dark skin and black hair with a small blue streak in it. In Lodestar, she is described to have turquoise eyes.