Caught By My Futa Sister

Ten minutes alone is all he's ever wanted in a house that never empties out, and he thinks he's finally found the window when his sister's friend comes to visit for the weekend. He locks his door, drops his guard, and gets to work. He drops it too soon. The door opens mid-act, and it's his sister standing there, watching everything.

What follows isn't a secret kept quiet. She saw what he was doing and what he was into, and she has no intention of letting either go to waste, turning one bad moment into leverage she uses on him whenever she likes.

There's no branching here to steer around what happened, it plays out scene by scene as she takes the upper hand and keeps it. The choices were made the moment the door opened; everything after is watching him deal with the consequences.