Cum in Kelly's mouth.

(This chapter inspired by ayyar, who wanted Kelly to savor the taste of your cum. I'm taking that idea and playing with it a little.)

"I'm going to cum, Kelly," you say with a moan. "Please keep sucking my dick until I cum in your mouth. Please keep my cum in your mouth and do not spit or swallow until I specifically tell you to. Please try not to let any drops of cum escape from your mouth."

"Mmm! Mmm!" Kelly says in a bit of a panic. However, because of your commands, she has **** in the matter.

Her head bobs up and down your dick as your bals start to clench. With one last groan, you start to shoot your load into your sister's mouth, filling it quickly. Because of your demand, she doesn't swallow. However, her mouth fills up quickly and some cum drips out of the sides.

Once you're spent, you slide your cock out of your mouth and Kelly immediately closes it so no cum escapes. She shudders a bit in disgust and glares up at you.

You look down at her, wiping your forehead. "Kelly, I'm going to conduct an experiment. Please answer my questions by nodding for yes or shaking your head for no. Understand?"

She nods.

"Remember, Kelly, you're still compelled to be honest with me. Do you enjoy the taste of cum? Do you like swallowing your man's seed?"

She quickly shakes her head.

"Disappointing. But I want to see if I can fix that. Kelly, please start swishing your mouth with my cum like you're rinsing your teeth with it."

Her mouth starts moving and she groans and shudders in disgust again.

"Kelly, please love the taste of cum. Please become obsessed with swallowing cum at least once a day, every day. Please enjoy the taste of cum so much that it's now your favorite taste in the whole world."

Kelly blinks and her face changes. She shudders again. However, this is a shudder of pure ecstasy.

"Now, my slutty sex **** sister. Do you enjoy the taste of cum?"

Her head remains still as she keeps swishing your cum around in her mouth. You start to wonder if your experiment worked when she nods her head the slightest amount.

You frown. "I need more of a confirmation than that. Kelly. Do you enjoy the taste of cum? Do you like to swallow cum?"

She looks up into your eyes, a little awed and a little scared. She nods at you.

You grin wide. "Excellent. You can swallow it now."

She starts drinking every last drop of your cum, even licking the area around her mouth to take in the drops still there. She leans forward and starts to voluntarily clean off your cock with her tongue. As she does so, she looks at you.

"How did you do this? *slurp* How the fuck is any of this happening? *slurp* How did you change my mind about cum? *slurp* What the fuck is going on?"

You almost pity her. You DID alter her own free will without a care for her. She's your sister. Maybe you should bring her in on your secret. It could be fun to have a partner in crime. Or maybe she'll just take the opportunity to screw you over if she knows. It's time to choose.