Fillie is the leader of the Cell Squad, an elite force of white blood cells in charge of saving the human body.
She is a neutrophil – a type of white blood cell that can eat invaders, as well as emit toxins that can kill invading bacteria. For the purposes of gameplay, since we have another character eating bacteria, we limited her to emitting toxins and being an area of effect character instead. I like to depict her as being vegan, despite her appearance.