They could have avoided all the violence and hurt they caused if they weren't both emotionally constipated idiots.

Ed silently reminds Riddler that he didn't really do such a great job with the emotions either before looking up to Oswald, frowning slightly. "No. Of course not. I stayed in Gotham for you. Riddler has never had even the vaguest interest in even befriending anyone else. Ever. When Kristen die- when I killed her, I didn't feel guilty or bad for it and I certainly didn't grieve. Isabella... I was angry you made that decision for me. Lee, Lee was kind. I didn't know what that was. It was hypnotic." Especially after Oswald's mockery. Lee's kindness hadn't been very kind, but it had been more than Ed had ever really known.

He doesn't look at Oswald as he speaks, watching the fire instead. It's easier. "Then you threw yourself on that grenade for me. I knew you'd kill me for, that's nothing, killing's easy for us. You- you were prepared to die for me." And that was something Riddler still didn't understand and Ed struggled to believe, even with the evidence.