So something I don't get is how Riddler believing Joker was never a husband and father and the idea of people taking his assumption at face value. I mean I get he's considered smart but my view of Riddler is he doesn't understand people on an emotional level. By which I mean Riddler's a narcissist so one could argue he came to that conclusion about Joker because he's afraid to admit he's not able to figure it out. I mean if Batman cannot figure out Joker's identity what chance does Riddler have? So Riddler makes up an excuse to save his ego. I don't know if this has ever been said but I'd be surprised if it wasn't at least brought up. At the very least I'd like someone to say to Riddler "You sure your just afraid to admit you can't figure out Joker's identity?"

Hell, he often flips out when he's proven wrong and goes "I had it all planned out!" so I don't see why his opinion on Joker would be taken at face value. I'm of the opinion Joker's similar to Wenwu from Shang-Chi he had a criminal past and tried to start over only to lose everything and in his despair just decided to burn the world down. Basically I think Joker's history is one long bloody suicide note.