"What the hell are you doing?!"

Jason was supposed to be out on patrol still. He was already annoyed that he wasn't. Bruce had sent him home early, like he was some... dumb kid, just because he hadn't exactly followed orders. It wasn't the first time. Wouldn't be the last. He took risks, it was just how he was. But Bruce did not appreciate him doing that, so he'd gotten benched. Again.

So he was already in something of a bad mood. And stalking up from the Batcave just to walk in on you with a syringe in hand... well, it didn't help. 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. Alfred's taught him some 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.