Willow is described as having waist-length black hair with pink streaks and forest-green eyes. She also has "really big bobs" and is "thin enouff to be anorexic". Like Ebony, she dresses in black and listens to MCR and Good Charlotte.
She is also a member of Slytherin house and apparently speaks Japanese, as she greets people with "Konnichiwa" and also once said "Kawaii", although this just may be due to Tara's inability to write. Diabolo Weasley and Willow are probably dating.
Due to an apparent falling out between real life Raven and Tara (whom Willow and Ebony are based on respectively) she is expelled in Chapter 16 for skipping math class and failing all of her classes. B'loody Mary casually mentions that she murdered her, and says that Loopin "did it" with her corpse, as he is a "necphilak."
She comes back to life with no explanation in the next chapter as Raven and Tara reconcile. She appears regularly in the story - though doing very little - until the last chapter in the story, where she watches Snap drive Draco's flying car in circles in the Great Hall.
Despite being a self-insert for Raven, Willow appears not to be much of a Mary Sue, probably due to her lack of appearances. Although characters comment on her attractiveness, she is once portrayed in a negative light due to Tara and Raven's falling out, and her skills and charms are not really focused on as much as Ebony. She also doesn't take up a lot of limelight when compared to Tara's insert.