Marina Bruni is Marisa Bruni's older sister.

Marina looks like Marisa, although with several distinct differences. Marina is a failed hybrid. She is fully functional as a person, but she exhibits scales on her neck, has vestigil gills, and the right side of her body displays a successful transformation to aquatic capabilities. The left side appears normal. At first, Marina's hybridization seemed to have failed, and she worked in the upper levels of Corona Tower. Once her changes became too obvious to hide, she was assigned to Basement Level 3 to live in the quarters assigned to failed hybrids (the ones that can still function independently). Marina refuses to acknowledge her aquatic adaptations, and she keeps her body turned to hide them. One drawback to Marina's failed transformation is that she must spend at least an hour a day partially submerged to hydrate her skin. Moisturizing creams can extend the time she can be out of water but are only a temporary solution.

We learn of Marina's existence in Book 1 of The Human-Hybrid Project, but we first meet her in Book 2, Inside the Darkness.