The 14 year old boy NAME_1 won a bet against his cute 13 year old little sister NAME_2, who now has to submit to his every whim. NAME_2's boobs started developing last year, were yet small. Her butt was still a small girl's butt, a tuft of hair crowned her otherwise smooth pussy.
Next day NAME_2 comes into NAME_1's room to wake him for school. She notices his morning wood and already knows what's coming next. "Good morning, sis. I'm horny. Close the door and get naked, please.", NAME_1 says to his little sister. "Also, put on this blindfold", he adds. While she's kneeling in front of him, naked and blindfolded, NAME_2 hears him jerking off and quiet shutter sounds of a camera. "NAME_1, no pictures, please...", she says. "Here it comes, you slut!", he exclaims, cumming on her face and cute little tits while taking pictures. "Sorry for the 'slut' and the cum in your face, sis, spur of the moment.", he apologizes.
Flesh out and embelish the story.