"What?!" and then Zuko realizes that his volume hadn't gone down at all. So he tries it again in a harsh whisper after glancing at some people passing by. "What?"

This... this is crazy! How can they be in the future?! How are they even here at all! Why would the spirits bring people anywhere?

But instead of asking these questions just yet, Suki's gets his attention.

"Uh... sure?"