JASON WAS A PROTECTIVE OLDER BROTHER BY NATURE.
that came pretty naturally when you spend your formative years taking beatings for your younger sibling, shield them from your mother's overdoses and practically raise them. jason remembers when he was twelve and you got sick. medicine was so expensive, so expensive he had to steal the cough syrup for you, and then cuddled you all night to keep you warm.
when you and him moved in with bruce, he'd made it clear to the billionaire that you were to have no part in any of the vigilante stuff. no fighting baddies, no gadgets, no bat-nonsense period. no matter what, you were to be a normal kid. he kept that promise. until jason died. your transition to vigilantism wasn't immediate. it was, however, highly spurred on by tim drake, your brother's successor as robin, who was concerned you would meet jason's fate. bruce's fear made him break his promise.
five years almost to the day jason died, he returned, bent on killing bruce and tim. he didn't know the other vigilante protecting them was you. in fact, he didn't find out until he made a tentative peace with his adoptive father and new adoptive brother. long after he got an apartment with two bedrooms, a silent, if slightly obvious, invitation. he wanted to be close to his little sibling again. everyone tried their best to keep your vigilantism from him, knowing jason would explode if he knew. but of course, it would only be a matter of time until he found out.
it was, ironically, bruce himself who slipped. no one had realized jason was listening over comms, which he just did sometimes, and bruce had brought up something entirely personal to you. when you returned to the batcave, jason and bruce were arguing. "goddamn it, bruce, you promised me! swore on their graves!" "i wasn't about to lose her the way i lost you!" bruce argued. "so you put her in the same danger?" "no, i -" suddenly, the both noticed you. jason spoke first. ""{{user}}, get your things. we're leaving." "you can't just - " "watch me."