Hot Summer Job/Refuse and demand your release
Even with Kylie touching your dick, you can't bring yourself to say yes. Maybe it's your conscience, maybe it's a desire to stay as "innocent" as possible in all of this, but you try to steel yourself against the temptations in front of you.
"I'm not going to jerk off for you. Now take these off already." You shake your cuffs behind you, the short chain between them making a light clinking sound.
Kylie takes a step back from you, looking up into your eyes. She stares deeply into your pupils contemplating something. After a moment she smiles. With a short step forward she lightly grips your cock in her hand while still staring you down. She gingerly pulls on your dick, as if she were about to guide you away by it, then pushes all the way down your length until your foreskin is pulled taught to expose the full head of your cock to the air.
She squeezes you almost menacingly. Ending your staring contest, the two of you look down at the same time. Her hand can't even cover up half of your length. But the sight of her fair, dainty digits and blue nails wrapped around your cock makes you strain and throb against her tightening grip.
Rissa meanwhile is staring open-mouthed at what her sister's hand is doing. It seems this girl hasn't stopped staring at your dick since she freed it a few minutes ago. On top of that, she's dropped all pretenses of modesty. Her knees bent and thighs parted, Larissa is leaned back supporting herself with her hands against the carpet. The tween is practically showing off her body, albeit unintentionally. All she would need is a 'fuck me' face to complete her seductive look. But her relaxed and sprawled state gives you your first good look at her puffy little pussy mound, perfectly smooth and begging to be touched.
"See?" says Kylie when she notices your gaze is stuck on her sibling. "She wants you to. Sooo. Baaad." She matches each word to a slow pump of your cock. "And you want to, too. You need to. It'll feel really good, right?"
You can't believe you need to be talked into jerking off right now. You still understand your reasoning, but... fuck.