Is it possible that Joker is an enemy of the Court of Owls? I thought about this after reading both Endgame and the Court of Owls Volume One. Something stood out to me when Batman went to the Court of Owls thinking they'd know if Joker really had been around for so long. I thought about how odd it would be for them to know anything about Joker. I mean yes they've been around forever but that means absolutely nothing. For example if Joker was immortal and had been around forever whose to say he didn't know about the Court of Owls already and thus knew exactly how to avoid their notice? I mean the whole reason Batman never knew about them was that they had been around a lot longer and knew how to hide. Why couldn't the same be said for Joker?

Another thing that I've thought about Joker is that he is known to kill indiscriminately and at random. What if that isn't actually the case? What if he's been secretly assassinating members of the Court and has been disguising his assassinations in the form of mass murder and mayhem and because it looks random the Court hasn't noticed? It's like Sherlock on Elementry once said that Apex predators don't have the luxury of imagination (meaning they can't imagine something actually being a threat) that could be the Court's major down flaw.

I started thinking about this when I saw what was happening to Bruce in the Labrynth the Talon kept chasing Bruce, luring him to a camera and saying over and over to smile. What if that's what happened to Joker? What if he was in there going through the same torment dying again and again until The Court final thought he was dead when he really wasn't?

As for why he hates Batman maybe he thinks Batman is affiliated with the Court of Owls? At the least I think it would make a good what if story or else world's story. Also if Joker was immortal and had history with the Court I doubt current members would know most would probably chalk stories of an immortal man to superstitious non sense. Much like how Batman dismissed the Court in the beginning.