[He blinks at the reaction, but the strongest emotion that remains in his expression after that is a bit of confusion.]

It's to prevent infection, so the wound won't get worse before it gets better. I'm sorry for not warning you, I suppose I thought you were familiar...

[He thought maybe she was used to being patched up... by someone who had maybe five minutes of medical training, at least? Good gracious, if she doesn't even know what this is...]