The Legend of Korra, Book 3: Change

Aiwei:
Allow me to introduce the matriarch of the metal clan, Suyin.

Suyin:
Please, call me Su. Great to finally meet you, Avatar Korra. And this must be Mako, Bolin, and Asami.

Mako':
You've done your research.

Suyin:
I make it my business to know who's visiting my city.

Korra:
So you're a dancer?

Suyin:
Dancer, leader, wife, mother, collector of rare meteorites. You'll find people here have many skills and interests. [Aiwei whispers something in her ear] Korra, why did you lie when Aiwei asked if there was anyone else with you?

Korra:
What? I-I didn't. I mean... How did you know I was lying?

Aiwei:
I am a truth seer. When people lie, their heart rate and breathing increase. I can sense the most subtle of changes.

Suyin:
Thanks to Aiwei, there are no secrets in our city.

Korra:
We came with Republic City's chief of police. She didn't want anyone to know she was here. I'm sorry I didn't tell you.

Suyin:
Lin's here? Well, I would love to say hello.

Korra:
Wait, you two know each other?

Suyin:
You're joking, right? Oh, Lin never told you about me.

Korra:
No. Why would she?

Suyin:
I'm Lin's sister.