AU where Batman has a "no killing" rule but that only applies to Batman
Bruce understands that people have their own form of morality and justice. He's not going to fault a soldier for doing what they have to do to protect people. It's just that he personally would probably never go that far. Not that he can't, mind you, he's fucking Batman! Just that the mental and emotional toll would fuck him up so bad he'd be a danger to himself and society.
So when it comes to his murder happy children his rule for them is: "Wait until you're 18."
Bruce: "Dickie, I know Tony Zucco killed your parents and he deserves WAY worse than a punctured lung, two broken legs, a fractured skull, and a dislocated shoulder. But you're also 10 yrs old and the parenting books say that murder at such a young age is not good for a child's emotional development. So how bout we keep him locked up in jail, good and tight, and if you're still mad about it when you turn 18 then you can have at it. Sound good chum?"
Dick, pouting and kicking rocks: "I guess."
Tim "forever 17" Drake is just counting down the days until his 18th birthday because that mother fucker has a list. He doesn't mind waiting because he god damn knows there are worse things than death one can do to someone.
Damien has been killing since he could walk and hold up a sword, so when he comes to live with his father under the "no killing until 18" rule he is NOT happy about it. Until his brothers start poking fun at him.
Damien, pouting: "It isn't fair! Todd gets to go out and kill people!"
Bruce: "Jason is over 18 yrs."
Jason: "Yeah! And besides, its not my fault you're just uncreative in how you beat up bad guys!"
Damien: "What is that supposed to mean!"
Tim: "It means that there are worse things than death but you're just too dumb to know it."
Damien, furious: "Am not!"
Jason and Tim, teasing: "Are too!"
Damien: "AM NOT!"
Jason and Tim: "Are tooooo!"
Dick, tired: "Guys, stop making fun of him. He's just gunna take it as a challenge."
Damien, determined: "Well I accept this challenge! I'll provide my superiority as a vigilantly by taking out the enemy in non-lethal yet appropriately brutal ways of punishment! Just you watch!"
Bruce, weary yet appeased: "Well at least he's not gunna attempt murder for a while."
Jason didn't come with an automatic kill switch so Bruce didn't really have to worry about it. But then Jason died and Dick got to see first hand as to why Bruce had a no killing rule for himself. The insurmountable destruction, the overall apathy for the harm to others around him, the deep seated rage ready to just destroy everything he comes in contact with. Alfred tells Dick that they need to stop him because Bruce won't just stop at the Joker, he'll go after Jason's mother (in this au I'm making Sheila live for the extra angst factor)and whoever else he deems even remotely responsible for the death of his son. Bruce won't care if it starts wars and conflict across nations, he will NOT stop until he gets his revenge.
So they stop him, practically have to sedated Bruce with enough tranquilizers to put down an elephant 10x over. And then they lock the Joker up in the deepest underground pits of Arkham with a broken spine and enough security measures that it's very much impossible to brake him out least you're the Batman himself. Bruce isn't happy about it at first but Alfred and Dick are there with him through it all and it helps a lot.
When Jason comes back he still doesn't know about the "no killing until your 18" rule, nor does he know the reason WHY Batman doesn't kill. So he's still angry and does his whole thing as Red Hood but when he reveals himself to Batman as Jason Todd Bruce is just so happy to see him again. And Jason is confused cuz like: "I just killed a bunch of people, aren't you disappointed?"
And Bruce is like: "I am a bit mad that you hurt Tim but other than that you are technically over 18 yrs old now so I'm going to assume you understand the weight and responsibility that is put upon you when killing someone."
Jason, softly: "What...the fuck?"
Then Jason quickly snaps back into gear with his plan, demands Bruce to choose between killing the Joker or him and Bruce hits back with: "Oh, I'd like nothing more than to kill Joker but I promised Dick and Alfred I wouldn't after almost starting an international war that one time."
Jason, extremely frustrated that his plan isn't going how he wanted to: "What. The. Fuck!"
So Jason dips and tracks down Dick so he could explain what the hell was going on. And Dick does explain. He explains the absolute monster Bruce almost turned into when Jason was murdered and how Bruce would most definitely not stop at the Joker if given the chance.
Dick: "You don't understand Jay, it was bad! Like really, really bad! He was going to kill your mom!"
Jason, shocked: "The fuck?!"
Dick: "He still has her on a tracker! We found him just before he killed Joker, but he still managed to paralyze him from the neck down!"
Jason, slightly disturbed: "That was him!"
Dick: "He was beating Joker's ass with a crowbar! And even after we managed to sedated Bruce and pull him off the clown we still had to make sure that Joker was locked up good and tight underground because if Bruce even caught a glimpse of him in a photo he'd go into another spiral!"
Jason, horrified: "What....the fuuuuuck???"
