"What the f*ck are you doing?!"

Jason hadn't really planned to swing by tonight. He certainly hadn't announced he was coming. Not unusual really - he tended to just 'show up whenever' and 'leave when he felt like it'. Sure, Wayne Manor was a home to him, but... well. He didn't stick around all the time. For a variety of reasons. So it's not like you knew he was gonna come strolling up from the Batcave out of nowhere. But maybe that made it a bit worse, made it feel more secretive, that you'd expected to be alone, everybody else out of the house. Finding you with a syringe in hand... well, it was a shock, to say the least. Because, well, he doesn't like needles.

He knows, logically, that there's plenty of perfectly valid reasons one could have for such a thing. He's learned some basic medical stuff. Lots of necessary, prescribed, safe medications are administered by injection. He doesn't really know enough to guess at which ones - insulin, maybe? Hormones? Blood thinners and crap like that? - but he does know that. Heck, if he'd thought about that he might've even been upset for different reasons, because maybe you're sick or something, and you need some sort of medication, and he should be worried about you. But in the moment? That's just not where his mind goes.

Instead, it went back to being a little kid, and seeing people using needles like that for not so safe stuff. To the fights and the screaming and the strangers demanding money and the stuff he had to do to get it. To walking in on his own mother, multiple times, and especially the last time, and...

Yeah, maybe he panicked a bit before he actually thought about anything. Maybe he's crossed the room to try to snatch the syringe away from you before his brain's fully caught up with what he's doing. Maybe he's yelling before he's given you any chance to explain. But he's not exactly taking the time to think rationally right now.