I hc that Jason is always calling Bruce "dad" by accident. It pisses him off because he's been trying to stop for years but literally can't. In his head Bruce has always been "dad" or "old man" and it's an ingrained habit at this point. Jason is the only one of the kids who consistently does this. Everybody else doesn't have this problem and only calls Bruce "dad" when they want to. Jason is a loser who is always slipping up.
"You never understood! I'm no one's son, dad!-bru-batman! Fuck you!"
"Da-fath-pops-fuck! Never fucking mind."
"Oh yeah, I just need to see if my da- Batdad- fuckin hell. Batman-"
"You're not my father, dad! Shit! I mean Bruce! Stop laughing!"
"Dad- no no batd- fuck it. Dad, I need money. No it's not for anything illegal I swear."
"Oh sweet! Dad, come look at this! Wait no- ew wipe that look off your face. I hate you."
"Hood, can you pull up the schematics for the case?"
"Sure thing, Batdad-I mean! weird reclusive man I lived with for a few years that didn't let me wear pants to fight crime."
"You said you wanted to be just like Dick thou-?
"Shut the fuck up, Dad! He's right fucking there. I hate you."
"Batman said you weren't allowed to kill!" - random criminal who is about to get his shit rocked
"I don't give one shit about what Dad says. " - The illusive and terrifying Red Hood