So, before any official announcement from RS, eveyone was speculating that the stolen property acheivement (I think that was the title for it) that had the description "no crime fighter should be without this" was referring to a utility belt. I haven't read the threads so forgive me if this has been brought up already. I believe that this is referring to a "side kick", or more specifically, in this case, Robin. I'm guessing Robin is kidnapped by Harley and that draws Batman back into Arkham City to rescue him.