Incest Seduction/Grope Kim's other breast

Emboldened, you glide your hand to her other breast squeezing it more eagerly than the first. Kim's flimsy bra does little to prevent you from manipulating her breast in your palm. Your lust is slowly taking over as you knead and explore your sister's chest.

"Okay," announces Kim, sitting up onto the couch. "We're even now."

Your hand is still under her shirt but it slid down onto her skin when she pushed her way up. Her ears are burning red. Her cheeks are flush. Is she embarrassed? Maybe she's getting cold feet. Or maybe she had no intention of going any further.

You pull your hand away, taking the liberty of running your fingers along her lean bare back before leaving her shirt, then try to straighten out your lap. Unfortunately your lap is plenty "straight" already. Your cock is rock hard now, poking straight up in your sweatpants and advertising your erection to the world. The front elastic of your sweats is being pulled away by your cock leaving a tiny gap between your pants and your stomach. Kim giggles softly beside you.

You're about to reach inside to deal with yourself, but then you pause. Apparently Kim finds this hilarious.

No need to embarrass yourself any further. Better sort this out.

Just chillax. Guys pop boners all the time. Besides, it's her fault.