In this adult sibling role-play, one sister is outgoing and slightly dominant, while the other is shy and mildly submissive. By the time I discover their true desires, both have already locked onto my cock. Since I am secretly involved with them, they seduce me at every opportunity during daily life. Eventually their shared taste for my huge cock sparks an all-out rivalry. I cannot choose because they are both cute and sexy, so they force me into a threesome and decide that whichever sister makes me cum first wins.