Incest Seduction/Move your fingers lower

You inch your fingers lower, little by little, until the tip of your middle finger finds a crevice in the mound under her yoga shorts. Your sister draws a deep breath and somehow pushes her hips even higher into the air. You push your luck, sliding your finger down the length of her slit while your other digits press down on her lips on either side. You're only there a few seconds before Kim chickens out and lowers herself onto your lap.

"I... I meant harder, not... 'lower'." She says, blushing fiercely. Kim throws her arms around your neck but only manages the odd glance at your eyes. "Silly brother..."

Your little sis really is gorgeous. It's not that long ago that she was a brace-faced acne ridden preteen. But not anymore. Seeing her pose and stretch seems to have flipped a switch in you. You slip one hand around her side, grabbing her hip and pulling her closer. "I only did what you told me to. I don't know anything about yoga."

Kim shifts in your lap, then freezes unexpectedly.

"Umm... speaking of 'harder', you aren't, umm..."

You raise an eyebrow but say nothing. You want her to finish.

"...are you getting a stiffy? Because of me?"

"Nah, I'm always hard," you respond, flippantly.

"Ah." Kim deftly passes one of her legs between the two of you so she can straddle your lap. "Is that what the girls down the hall have done to you?"

"No. I just find it easier to stay semi erect at all times. It can be a real time saver."

Kim smiles and wiggles her butt around teasingly. "Really? So this is 'semi erect'?"

You shrug. "Thereabouts."

Kim giggles and gives you the naughtiest look you've ever seen from a girl as adorable as her. She runs her hands down your chest, finally able to fully look you in the eye.

"You know what I think? I think I got you hard. I think your itty bitty widdle sister gave you a stiffy!"

Reply "And what if you did? What are you going to do about it?"

Reply "Honestly, I'm just hard 24/7. But you sound proud of yourself!"