The weapon

Sokka circled Azula, feinting with his sword a few times, but Azula showed no sign she even knew he was there.

He poked her forearm with his sword, drawing a drop of blood. She didn't move.

"What... happened?" He said, totally confused.

Azula spoke, her voice neutral, more calm than Sokka had ever heard. "I inhaled the mind control gas. I am fighting its influence but it is incredibly strong."

The words hung in the air for several seconds. "Mind control gas? Explain yourself."

She did. She told him the whole story of how the Fire Nation had gained knowledge of mind control from the Earth Kingdom's Dai Li and improved on the concept. They had spent months developing a formula that could crack open a person's mind and leave the completely suggestible. She explained that she was currently totally helpless and would be defenseless to resist any suggestion he gave her. The effects would last a few hours and then she would begin to return to normal. It was unclear whether the suggestions would stick, then. Sometimes they did; sometimes they didn't.

Sokka couldn't believe it, but then, the evidence was right in front of him. He took a shot, still holding his sword between him and the princess. "You are my prisoner! You will submit to my authority. You will not resist me, fight against me or any of my allies, or seek to undermine my mission in any way. And no fire bending!"

She nodded. "Yes, I am your prisoner. I will obey."

"Get on your knees." He instructed.

Azula sank to her knees with her usual perfectly controlled grace, still staring blankly ahead.

Sokka tossed a pair of wide manacles to her and instructed her to put them on behind her back. She folded her arms across the small of her back, pressing her forearms into the cuffs so they closed around her limbs. Sokka heard the tell-tale click-whirr of the device ratcheting down hard around her limbs. He'd invented those himself; there was no way she was faking being bound.

Sokka was beginning to fully believe that there was some potent mind control involved. This had to be the weapon he'd heard about. He ordered her to lie down on her belly and she responded obediently as before, falling slightly due to her bound arms. Without rolling onto her back, even the skilled Azula would have an extremely hard time rising suddenly. She wasn't threatening any more. He sheathed his sword.

"Where are my men? Do you have more of this mind control gas? How many soldiers do you have?"

Azula told him everything. His men had been taken prisoner. There were another dozen or so doses of the gas in their base not far from their current position. She had three dozen soldiers.

Three dozen. There was no way he could take them all, and even having Azula as a hostage wouldn't guarantee he could get in and out safely.

He thought hard, considering every option. He couldn't believe the powerful Azula was bound on the ground at his feet. She was indomitable. Fearless. Terrifying. Brilliant. She was always one step ahead; it was a miracle he'd defeated her at all.

Wait. Azula. It was so obvious.

He formulated a plan. It hinged entirely on the fact that Azula had been telling the truth about the mind control gas. He removed her arm-bindings.

"Azula, you're going to help me take down your whole operation."

"Okay."

He looked at her, feeling suddenly mischievous. "And call me Mighty Sokka. I'm the best warrior in the world, after all."

"As you command, Mighty Sokka." she said, her voice still annoyingly neutral.

"And put some heart into it. You sound super weird. It's freaking me out."

Her expression shifted, her voice softened to a sultry, almost affectionate tone. "As you command, Mighty Sokka."

It stirred something in him, but he cleared his head to focus on the mission.