Incest Seduction/Continue the bare back rub

Yes, it's just a back rub. Until it's not. Besides, Kimberley doesn't seem concerned. She didn't even flinch when you pushed her bra away. You're just a bro and his sis, laying on the couch. Even if she's close to topless...

You glide your hands the rest of the way up her bare back. Intimately caressing her soft angelic skin is captivating you. And the harder you get, the more of her that you want to be touching.

You skirt your fingers down her sides, part of you wanting to slip a hand around to her front and onto her tit.

"Hee hee hee! That tickles!" Kim laughs, squirming in your lap.

"Oh, sorry." An evil grin forms on your face. "Does this tickle?"

You land your fingertips on the side of her rib cage and send them fluttering. Kim tries to hold back her laughter, clamping her arm down and rolling her face across your crotch and, consequently, along the growing length of your dick.

"Staawp!" she whines into your pants.

"Okay, okay," you relent, leaning back on the couch.

She cocks her head up at you after a moment, timidly asking, "You're not done yet, are you?"

"I suppose not!" you reply.

Kim smiles then pulls herself forward slightly, her arms moving around quizzically. It takes only a few seconds before you see her lift her bra into the air with two fingers. Stretching away from the couch she delicately drops it onto the floor before assuming her previous position with her head nuzzled over top of your cock. A cock that has grown another half an inch watching her throw away her bra.

"That's better." She sighs. "It was starting to poke me!"

That's not all that's poking you.

"Yeah, so..." you clear your throat again. "Was there something in particular that you wanted?"

"Hmm..." she hummed. "You should go lower."

"Lower?" you echo back.

"Yeah, lower."

"How low is 'lower' exactly?"

Kim snaps her head back again. "Don't be weird about it, Z. Just put your hands on my back."

You quickly comply, firmly placing both palms against her petite upper back.

"Now keep them on me and work your way down..."

Your hands creep forward with painstaking control and precision.

"...and don't stop until I tell you to."

Yeah, but what does that mean?

You follow your little sister's orders, gradually sliding your hands down her back with tender, even pressure. Taking in her slender waist as it shrinks beneath your fingers is tantalizing. But as you meet her gentle hips and start to move out again you experience trepidation; you're approaching her yoga shorts. She is going to stop you from massaging her ass, isn't she?

...isn't she?

Your fingers are about to bump into the edge of fabric protecting her rear. You should probably do something.

You're going to do exactly what she told you to... go lower.

This is as far as you go. Massage her lower back and leave it at that.