AU where the real reason Damian has a grudge against non-blood brothers is because a long time ago Talia told him Jason was his brother and Damian loved him for that but then Jason "abandoned" him (left the League and seemingly forgot about him) and Damian has been holding a grudge ever since
Meanwhile Jason either (a) lost his memories of his time in the League prior to being dunked in the pit, or (b) he just believes that Damian had been too young at the time to remember and so he doesn't bother bringing it up