The weight of their secret presses down on them as they steal glances, their breath hitching in their throats. The brother's eyes linger on his sister's curves, her body language inviting yet hesitant. She catches him looking, her cheeks flushing, but she doesn't look away. Instead, she bites her lip, her tongue darting out to wet it, a clear invitation. He swallows hard, his cock twitching in his pants, the battle between desire and morality raging within him.