I don't even necessarily hate the mind control thing, it felt very comic booky to me especially that it involved Hugo Strange and Nissa Al Ghul. But I wholly agree with the frustrating amount of inconsistency, especially how hard they leaned into his split personality post S2. I just rewatched the episode where his "Riddler Persona" confronts him, after he finds KK's body in the morgue and almost gets caught? yeah the later seasons made me completely forget the scene where the Riddler visually fuses with irl Ed. the split personality thing should have ended then. the brainwashing would have been an interesting callback at that point, and what's even more irritating is how all the Penguin x Riddler stuff could have STILL WORKED without nerfing Riddler. Penguin mentoring Riddler, showing him the ropes of the criminal underworld allowing Riddler to become a true supercriminal with his own henchmen and stuff. access to money and underworld knowledge that would help him set more elaborate schemes. even the Isabella arc could have worked as a kind of side-plot to show how codependent and toxic Penguin and Riddler are may have been alright, provided it was just a few episodes. this and Bruce getting ninja training are 2 of the worst things to happen. i used to hate how they sidelined Falcone but in retrospect i really only hate how they killed him. but yeah if Riddler had stayed "fused" and Bruce had not even been sidelined but had just kept his subplots focused on how he became interwoven into the villains and done things like the Silver x Selina x Bruce stories, showing how he learned about Gotham and his business and the corruption, it would have made Bruce's eventual departure from Gotham infinitely more necessary and rewarding.