[Alfred brings an envelope to Bruce, who's watching news reports on the Riddler]

Apparently, you and Batman have a common enemy. That was with the morning mail. [Bruce opens the envelope, revealing another riddle, the camera cuts to the two of them in the Batcave] "The eight of us go forth, not back; to protect our king from a foe's attack".

Chess pawns. Clock...match...all physical objects, man-made.

Small in size, light in weight.

What's the connection?

With all due respect, sir, I believe that's why they call him "the Riddler".