[The last time she saw him?? Now who's the delusional one?]

But you look my age, and Aang's been gone for ages now. You can't have met him unless you're ancient like Katara is! [And that's really ancient--no offense to her Sifu.]

Oh, wait. I know! You're from their time. Like Sokka is! [Korra loses all the hostility and practically bounces on her feet, now that she's figured it out.]