Katara, shivering and shaking and panting and sweating, looked down at Sokka. She saw that he had a bulge in his trousers, as he lapped up her nectar (to the sound of general approval from their audience), and unbidden the notion popped into her head to repay him.
After all, aside from being a boy toy, he was also their ho. And a ho couldn't do that sort of thing for free.
So, smiling and licking her lips, Katara commanded Sokka to stand up and drop his trousers.
"Sure," he said, finding nothing strange with this request. And so he did exactly as Katara said, standing up and letting his pants and underwear drop to the floor.
Katara and the other girls gasped at the size of Sokka's cock when they saw it spring out of his trousers, stopping just short of smacking his sister's cheek.
"Wow..." Katara mumbled, a little overawed by the sight. It was nothing like she had seen before, the few times she had gotten a look at him naked since they were little kids. "It's huge..."
Yue, Suki, and Ty Lee all nodded in agreement. Toph and Azula licked their lips.
Katara smiled.
"Here's your payment, Sokka," she told him, giggling nervously for a moment as she eyed his massive member. After a moment of staring, Katara eventually managed to work up sufficient courage, and she took the dick into her mouth.
Or as much as she could, at any rate.
But it was enormous, bigger by far than anything Katara had seen before, in her relatively limited experience, and it was all she could do not to choke herself on his dick only a third of the way down its length. She could not fit any more of him into her mouth than that, and so she bobbed her head up and down the tip of his cock while stroking and squeezing the rest with her hands.
Sokka groaned and shivered and bucked his hips under his sister's ministrations, and soon he came, filling her mouth with his semen, which she swallowed with a contented look on her face.
What next?