If Jason Todd had not died in any way while he was a kid or while he was Robin, then Bruce would not have had as many children. I don't know if anyone else has thought of this, but besides Damian, every other sibling was basically a result of Jason's death. Bruce wouldn't have Tim, airgo Steph. That would probably cross Cass out (not as open to the Bats), same Duke, since by the time he came around, there probably wouldn't have been a robin and he wouldn't have been fighting crime like he was (this means he probably got Joker gassed). Damian would likely never have come to Gotham, maybe dying to Ra's, maybe being sent somewhere closer to Talia because he didn't have a protector. This could even still work if Jason died as an adult, given that he wasn't Bat's Robin anymore, and had actually grown up when he died. Of course, it would hurt Dick and Bruce, but I'm assuming at this point, their relationship would have gotten better and they would actually lean on each other for comfort, not making Tim entering the family necessary. Obviously Barbra and Luke would still exist, same with the other Gotham vigilantes that aren't technically Bruce's kid, it's just the ones he's adopted emotionally or legally would be cut down to just Dick and Jason.
Say Joker didn't fully kill Jason, or maybe it was another Villain that kidnapped him, and he got away alive. Or Dick was on earth at the time, and he and Bruce decided to put aside their differences and rescue Jason. We could still get angsty Jason, just not necessarily to the degree that we see in other comic/shows/movies. We could still get a fight between Bruce and Dick and also probably Jason. Jason could still turn into the Red Hood, just maybe not so deadly (if anyone has read that one AO3 fic where they "have wings", you know what I'm talking about), where he chooses to be Red Hood and doesn't do it because he either feels like he has to or for revenge.
Anyone feel free to add into this, or correct me, because I very well could be wrong and the BatFam could just be canonically fated to happen.
