The Batman: 10 Ways The Riddler Parallels Batman
3. Their Trauma And Purpose Began When Thomas Wayne Died
When Thomas Wayne was alive, he was running for Mayor, and with his candidacy was the promise that he would give a fortune to the orphans whether or not he won the election. When he died, all those promises went out the window. It was not just Bruce Wayne who was effected that day - orphans throughout Gotham were also affected, including the orphan Edward Nashton.
The trauma of losing his parents set the path for Bruce Wayne to be Batman someday. So does the path for Edward Nashton to be The Riddler because he was promised a better life only for nothing to change.
His anger towards the social elites grew until the only thing he can see were their false promises and corruption. Therefore, he hates Bruce Wayne. He was an orphan but experienced none of the sufferings he endured because of the Wayne name. Instead, Bruce Wayne did nothing to help other orphans like him. He did not continue the Wayne legacy to help the community. He was too busy wearing a mask to beat up bad guys instead of doing actual change.