Your key is missing. Fuck. You're upset, but you're pretty sure you know where it is... Heading into your sisters room, she's on her phone and acting nonchalant. It's clear that she has it - this is totally bitchy sister response. Looking up at you, she smiles and asks what you want. Hinting about it, she has an awakening and admits to having it. You ask for it back, but of course she says no.

You've watched her in the shower, and she thinks that's gross. It's so weird that you lock your dick up in a cage, and she wants to see if you've trained yourself to not enjoy her naked body - KNOWING it's bad. Her idea is that you're caged for that reason, to avoid enjoying your sister...
Her own fucked response though, is to strip for you and fuck herself. She moans and tells you that you clearly want to fuck her. You wish you could, and she says you won't get the key if you begin dribbling out of the cage. It's not an easy task. Her actions and words clash, and your body is very confused.