Anna has an idea...

Anna needed a move that would break Billy, not just weaken him. Right now she had him pinned decisively, but it wasn't enough. She needed something humiliating, something he would dislike enough to beg her to stop.

She thought back to the moment earlier when she'd shoved her butt right in his face. He had reacted violently and immediately, pushing her away with all his strength. Obviously he wasn't a fan, although it surprised her that he wouldn't like her butt in his face when he liked it just fine staring at it from afar the last couple days.

As much as she was enjoying her current pin, she knew exactly what she wanted to do next: sit on his face. She cautiously brought her left leg up and around his head, getting halfway to her knees, ready to drop her belly straight on his face again if there was any resistance.

Anna felt the thrill when she realized Billy wasn't resisting. He was shaking his groggy head back and forth, but he wasn't moving the arm she'd freed from her thigh-prison. And his other hand, she still had pinned.

She moved into position, straddling Billy, facing his feet. He opened his eyes, groggy, only to see her panty-clad ass hovering right over his face. Now he finally moved his right hand, trying to block his face with it. She sat down on him anyway, folding up his right arm and pinning his hand to his own face.

Silently, dimly, Billy rejoiced at the fact that he'd managed to get SOMETHING between his face and Anna's butt. It wasn't that he wasn't attracted to the idea...but Anna's clever observation had resulted in her picking exactly the right hold. Ever since his mom had made him kiss her ass, he'd been mentally considering that the absolute low, the lowest and most subservient someone could possibly be. And although he could take it from his mom, since she was an authority figure, he really, REALLY did not want to be giving his little sister the ultimate submission.

But it wasn't up to him. Anna was going to TAKE that submission. She still had an iron grip on his left hand, and now she reached underneath her leg to grab his right wrist. Billy's arm was still feeling pins and needles from her thigh-lock, and it was nowhere near full strength. It was embarrassingly easy for Anna to twist his arm away from his face. She raised her butt up just long enough to tuck Billy's big arm between her thigh and calf, then before Billy could even say anything she sat her butt right on his face.

"MMMMMMMMmmmmmmmffff..." Billy moaned, his pathetic struggles muffled by Anna's luscious ass. She rubbed it enthusiastically all over Billy's face, causing more helpless moans and groans.

Anna settled in, starting to relax, knowing that Billy had no chance of escaping. His legs kicked weakly, uselessly, and his arms twitched but they were no match for hers. An overpowering sexual thrill surged through her, and she leaned forward and scooted a little backward so she could rub her panty-clad pussy on Billy's mouth.

Now Billy was reminded of Karen satisfying herself by rubbing her MILF pussy all over Billy's face. This was just a backwards, extra-humiliating version of that. But Billy couldn't enjoy it the way he did Karen, because again, he couldn't make himself accept the idea that he could lose to his little sister and get effortlessly dominated by her. Even though the evidence was sitting right on his face, he couldn't make it make sense.

Anna felt Billy's muscles flex as he made a last ditch effort, rolling slightly from side to side to try to knock her off of him.

She spread her legs slightly to improve her balance, which had the effect of her crotch pressing down harder on Billy's face, making him moan again. His struggles quickly faded as Anna cut off his air. She felt his fingers tapping lightly, yet insistently, on her thigh as he submitted to her.

"Oh, is that a submission?" she asked, giggling. "I don't know, we didn't exactly set up any rules beforehand, did we?" Anna made no move to let him out.

The taps became more urgent, Billy's hand fluttering like a trapped little bird. But Anna was ruthless, just rubbing her firm ass harder and harder against Billy's knocked-out loser face. The throbbing in her pussy was getting unbearable, but Anna knew she had to hold out just a few more minutes.

Billy stopped stirring, and Anna exulted for a few seconds, flexing her biceps despite the lack of audience, looking down in admiration at her own body. Who knew that a soft, curvy nerd like Anna could outwrestle and dominate a big boxer like Billy?

Then Anna turned around, resuming the same schoolgirl pin she'd hit him with when she first came into the room. She stared intently into his face, waiting for him to wake up, slapping him lightly with her hand.