What the– It's lucky for both of them Jack isn't armed with anything more dangerous than a bottle of whiskey that he is really not inclined to waste, as his first instinct is defensive. He doesn't just jump, he jumps and steps back against the wall, taking the bottle by the neck and raising it up level with his head before he so much as pauses to think.

And then he does pause. And think. Which does not actually clarify much.

"How did you even--" He's looking to the roof, then to Bruce. Dude, what.