Step sister found her tied brother and decided to take advantage

Girl came home and found her step brother tied to a chair with gag in his mouth. She started laughing at him and asking what happened. Turns out, that his yesterday lover has tied him to the chair at night and left. Maybe he wasn't good enough that she decided to make such prank.
But step sister didn't hurry up to untie her brother. She looked at his naked cock and decided to take advantage. Soon after, she was sucking his dick. They aren't relatives, so why not to have sex?