yknow what'll really piss off and send bruce to an early grave?
aot x dc crossover, but make it jason's dormant eldian genes suddenly giving him access to the coordinate bc of the underground mountain dew. throw in levi in there too bc im a sucker for ereri. a pit mad, angry, angsty teenage jason??? with access to many, many fucking knives??? in (mental) vicinity of a guy that killed 80% of humanity and the older guy who literally has a background in running notorious gangs in the underground and is the most proficient humanoid monster beheader in his time???
i imagine under the red hood being very, very different bc robin training in gymnastics and martial arts only amplified jason's skill in odm. im talking about revolutionary league engineered odm, and the fact that jason would definitely move too much like levi within the hella convenient cityscape of gotham, and fight like a mishmash of robin, league, levi, and eren. he'd basically be near impossible to identify using merely robin moves bc i very much doubt levi would let his new brat be predictable in hand to hand. due to levi's example, jason talks exactly like him, but somehow always speaks as vague and irritatingly assholish as eren.
the batfam are crawling up the walls in paranoia bc what kind of insane fucker would fuse katana sheaths, grappling hooks, and jet propulsion into a belt and use it to anchor into stone walls? why is he brilliant with that? why can't they recreate it? who the fuck is levi and how tf is he dictating this 'red hood' into sequencing a back kick to a spinning overhead kick within seconds in warehouses with literally signal blockers and no cameras?! (jason talks out loud to himself when in the mask. everyone will assume he has an earpiece on anyway) he assassinated a rapist by just lynching off the guy's nape while he swung by, that's insane. how tf does he never get dirt on that fucking leather jacket? who's "saint"??? is he the man in the chair? what does "i will eat your spinal cord" mean? is it a threat? a jest? is it a code for eren? is eren a meta? they once stalked red hood on a rooftop and saw him point to a centipede and said 'eren, its you. ' what does that mean!?
all while jason is in his apartment arguing with a hallucination levi like, "im sorry your teacup handle was trash but im not fucking holding mine like its a shot glass!... wdym why!? humans shed dead skin cells every second. im not drinking my tea with my dead cells polluting it!.. you dont get to form an opinion on why my teas are bagged and shredded when you fucking pulled me into the coordinate when the microwave beeped, old man!"
hallucination eren is the living room, reading the newspaper and plotting on breaking a bunch of human rights to tweak arkham asylum patients' genetics and memory into being as insane and carnivorous as normal titans without turning into titans. i mean, if eldian kings could make humans get the strengths of titans without turning them into one, he could definitely make humans have titans'n worst features. after all the shit that clown put jason into? yeah, eren is attached to his and levi's pseudo-son now, and god have mercy to anyone who'd dare to cross him again.
then when the confrontation with batman came up, its actually more brutal than canon bc eren definitely had his fun beating joker nearly to death via controlling jason's body for a while and bruce is horrified when joker wasnt even laughing anymore. he thinks jason already killed the joker, so he definitely flung that batarang with intent (and mostly out of anger but theres still intent), but it never landed bc
levi dodged and went feral. nobody fucking kills his brats ever again. not after eren.
yeah bruce did not come out of the hospital for nearly a year after that. he thinks jason probably came back wrong from his death and the general league of assassins issue, but nah he really just did an oopsie with the worst person possible to piss off. at least eren wouldve given bruce maybe 10 days to live then die very quickly, but levi wouldn't kill him just disable him... very thoroughly.