Incest Seduction/Pin Kim to the floor

With a grin you lift yourself off the couch and push Kim's legs forward. Your shove puts her into a somersault flipping from her front onto her back. But she has barely come to a stop on the carpet before you throw yourself on top of her. Your respective positions have put you into a sort of '69' grapple, but you quickly work to pin down her appendages.

"No fair! I wasn't ready!"

"Oh. Well are you ready for this?"

"For whaAAAAH-HAHAHAH!"

Your fingers flutter along her exposed stomach, right underneath your own. Screaming and cackling she rolls from side to side, her arms and legs flailing. You can mostly keep her skinny legs down with your other arm, but keeping her arms under control is a lot trickier. She pounds her fists into your butt repeatedly but that won't do anything to slow your assault. Then she latches onto your butt with her fingers, clawing deep into your ass-meat through your sweats. This is far more annoying, and verging on painful.

Scooping her legs up in one arm, you push your knees into the carpet and right yourself, lifting half of your sister into the air. She squeaks in surprise and lets go of you, probably expecting to be airborne at any moment. Instead you reach back with your free hand and grab one of her arms. Leaning to one side you stuff the arm under one of your shins then lower your leg onto her arm, trapping it there. Collapsing forward onto the floor you've left your little sister one less tool to free herself with, not to mention defend herself.

"Ugh! Meanie!" She pounds your butt again one-handed.

"Oh, I can get meaner!"

You reach under her own bum and scratch your nails across her yoga shorts. Involuntary squeals fill the room. Kim bucks and writhes, desperate to get away. She does manage to squirm her legs enough to plant her feet onto the floor and push her lower body into the air. Her thighs come up around your head, her crotch not far below your chin. But with your arm in the way she's not going to get any higher. For a split second you swear you can now smell something. Something moist. Something...

Kim is still thrashing as you haven't relented in the least. In fact, now that her lower half is elevated, there is even more room for you to work your fingers along her ass. So she thrashes even harder, her hand roaming across your own ass as if looking for a release mechanism. In a way she finds it. She locks onto your waist band and pulls back on it hard. The elastic stretches quite happily, exposing your bare-ass to your sister. You need to stop going commando.

"Hey! Quit it!" You pause only briefly before you continue your assault. Kim responds in kind, lowering your sweats as far as she can. You can feel the air rush under you, your cock and balls swinging between your parted legs in full view of your little sister.

"I can get mean too you know!" she teases, spanking your bare ass.

"Fine! If that's how it's gonna be..."

Fighting fire with fire, you quickly tear at Kim's yoga shorts, pushing them down her legs as far as they will go. Part of you regrets it as soon as you do it. Not that you're thinking all that clearly. But with a glance downward you find yourself staring not at a pair of colorful panties as expected, but directly into your youngest sister's snatch. It seems that Kim also chose to forgo underwear this morning.

"Jerk!"

You feel a slight tinge of guilt over what you're about to do, but you can't help yourself. You scratch at your sister's exposed ass, tickling her firm little bottom just as eagerly as you were a moment ago.

"BWAAH! HAHAHAH! HAHA! You- baaAAA!"

She can barely get a word in and you're loving every second of it. Granted, it's a very weird situation - both of you getting a close up view of each others privates, rolling around on the floor - and undoubtedly the naughtiest thing you've ever done with your sister. But at the same time you're having an awful lot of fun. Right up until she grabs hold of your balls.

"Woah!" You stop tickling, shocked by Kim's unexpected move.

"There!" she says in a huff, catching her breath. "Now it's my turn! Because when someone has you by the balls you're at their mercy... right?!"

This is nuts, but... why not? Play along with her.

Fight fire with fire, right? Grab your sister's pussy.

You can barely even process that Kim is doing this. Best you get off of her.