Encased in stone, Toph listens.
The thing about being a remnant Fire Nation governor of an Earth Kingdom province is that it makes you paranoid. The lord in question is pacing up and down the corridor directly to her left, and his advisor is saying something about how you can't trust any of these dirt-crawling scum, and you especially can't trust anyone who overthrows the Fire Lord and puts his puling little son on the throne and claims to bring the Avatar's peace. Or his agents. Lord Xianzu seems to have no trouble with any of these ideas. Yeah, maybe he's been listening to this advisor for too long, but if you ask Toph, not that anyone is, this place could do with a little more shaking up than just his sidekick.
The other thing about being a remnant Fire Nation governor of an Earth Kingdom province is that you weren't paranoid about the right stuff. Any Earth Kingdom governor worth his salary would have known that the holes in the walls of a stone palace aren't for heating ducts. They're for listening.
Just be discreet, Aang had said. Please, Zuko had added, and then had been really surprised when she knocked him feet over ears.
She can move around a little without opening up a new path, and the vibrations are clear down the whole mosaic of the corridor. She follows Buttface Xianzu and his pet whining caterworm to the end of it, where they decide they're in private and the advisor says, "I have the letters to call up Tianbei. They will rush to our aid in this war! All it needs is your seal."
Xianzu wavers, his hand going to his sleeve. "I--"
All the warning she gets is in the bolts on the door--the next room's all rushes--and then there's a huge clanging and clamor and riot of bells, and Toph, half-deaf and all-annoyed, takes the chance to break out of the wall to the other side. She heals it up just in time. As her ears kick back in she can hear Isaac saying, "We were told that you're the head honcho around here!"
"Top of the pops!" Miria confirms, and bangs a gong.
"The head of state!"
"The high and mighty! Oh, Isaac, it's so exciting!" Miria takes a step onto the mosaic and bows, in the wrong direction, straight to the vizier.
"Ah--What are you two doing here?" the advisor says, and Xianzu's face changes subtly. Toph presses her ear to the wall again, and catches all the way down to her feet the suspicious little sigh he lets out. She smiles. The advisor didn't correct them. If a beggar bowed like that to her steward back in Gaoling, and her steward hadn't fixed the mistake, well, they wouldn't have had a steward any more. Which is one reason out of like a billion she almost definitely doesn't miss the House of Bei Fong.
Paranoia is pretty great, actually. So is this "discreet" thing. So are witnesses to high treason.