Sienna is the wealthy, extremely popular former best friend of Lexi. Sienna runs the group of friends Lexi used to run, and uses her power to bully Lexi on a daily basis. Sienna holds Lexi responsible for the death of her brother, Steven, years before. When Sienna discovers that Lexi loved her brother, and has been visiting his grave for years, their friendship is rekindled, and Sienna brings Lexi back into the fold. But upon discovering what Lexi is, Sienna rejects Lexi's friendship and threatens to expose her if she ever comes back around.