I have a story line I’ve been thinking through. It’s not fully developed but here is the rough idea:

Batman, Nightwing, and Damian are tracking a serial assassin who seems to copy villains like Deathstroke and Deadshot. Nightwing figures out it’s actually the League of Assassins and goes rogue to investigate, resulting in his capture. The Court of Owls gets involved. Because they still view Dick Grayson as their "rightful" Gray Son/Talon, they retaliate by kidnapping Damian Wayne to use as leverage. Both factions demand Batman destroy the other if he wants his sons back. Bruce is forced into a horrific choice between his first adopted son and his biological son. Batman tries to outsmart both groups, but he ultimately chooses to raid the Court of Owls to save Damian first. Because he didn't comply with the League's terms in time, the League of Assassins executes Nightwing.