Now, the Riddler is increasingly interested in Batman and in proving himself smarter than Batman, while he also goes about a series of bombings and computer hacks to take down Penguin and all of Gotham.
The Riddler would have tattoos on his body of symbols and information about his bombs etc (and perhaps a question-mark tattoo around one eye?), all in cyphers and code that nobody but the Riddler can ever understand.