Thankfully, because the Riddler left himself vulnerable by staying near the crime scene, it doesn't take long for the GCPD to track him down and haul "Edward Nashton" over to the Arkham Correctional Facility. Yes, it's time for the typical "villain explains their plan in great detail" part of the movie. We joke, but Nashton's explanation actually serves a key purpose this time beyond lazy exposition: He reveals the true extent of the corruption that has gripped Gotham for decades, and forces the audience to face an uneasy comparison between himself and the Caped Crusader. You see, Riddler used to work for the Waynes' Renewal Project as a forensic accountant, and that's where he discovered the dark truth.
While the wealthy elite got richer by skimming from Renewal, Nashton was growing up in one of the orphanages that should've benefited from that money. Instead, the villain had to endure a horrific childhood in squalor with other underprivileged kids. He even says that babies died during the winter because the buildings got so cold. It's a haunting thought, one that makes Riddler's own quest for vengeance a little more understandable. But he makes a disturbing confession: He was only spurred into action when he saw how Batman was tackling crime on Gotham's streets.
Yes, Bruce helped give birth to the Riddler; he inspired the killer to take the leap into vigilantism, meaning there's plenty of blood on those bat-hands of his. To be fair, the film makes a point of showing just how brutal Batman is to the point that the civilians aren't even sure if he's a friend or foe. It's hardly surprising that other self-righteous folk would follow in his boot-steps.
Unfortunately, there's little time for soul searching here, since Riddler has already rigged bombs around Gotham's sea wall as the final act in his war on the city.
