Looking for one where she gets dumped by her boyfriend the day she was expecting to lose her virginity but still pent up and determined she goes home where she finds her brother about to jerk off or something but instead of being disgusted her horny brain takes over and she decides to do it with him. He’s too stunned by this to resist. Bonus if they had no incestrus tendencies before this
Does not need to be exactly this just a similar setup