Battle For the Cowl AU where Jason doesn't hear Bruce's will but does find out about his death which triggers a psychotic episode*, in which Jason steals the cowl, convinced it's Bruce's body and Bruce is simply sick, and takes care of it like a very sick patient and keeps telling Bruce to wake up.
Dick arrives convinced Jason is planning something nefarious with the cowl, and is blindsided to find a Jason who hasn't slept or showered in days, has lost ten kgs and keeps feeding an empty cowl cold medicine while telling it to hold on and it's gonna get better and sometimes he's calling him old man sometimes it's Batman sometimes it's Bruce sometimes it's dad and sometimes it's mom. He cannot stop shaking.
*psychotic episodes can happen in the context of bpd without necessitating further diagnostic classification; acute psychotic breaks can also happen during high stress situations, depressive episodes, high fever, extreme hunger, neurological conditions, some infections, etc, etc. Here it's due to the stress grief and bpd/cptsd.