If you take a look at the IMDB page for Batman: Arkham Asylum 2, you might spot that Vincent Martella is cast in the role of no one less than Robin, the caped crusader's innocent little sidekick. Vincent Martella has done such great roles as Phineas in Phineas and Ferb and most recently Hope in Final Fantasy XIII. Kotaku showed this information to Warner Bros, but the publisher claims to have no idea where it comes from - "To our knowledge, what you asked about is inaccurate information. We are not yet discussing details for the sequel."
Co-op in Batman: Arkham Asylum 2? Now that would be fun...