Alex came through the front door just as thunder boomed. It looked like he made it home just moments before a summer deluge hit. He wasn't used to Florida weather. The forecast was for a clear afternoon and then this. His father had remarried last year and the whole "new" family, had relocated from Jersey.
The forecast had been for clear skies. He had checked just before leaving for soccer practice, obviously that had changed. The rain hit just as he started upstairs. His room was at the end of the hall, just a bit farther down and across from his new sister's room.
As he went past her room, he noticed that her door was ajar. Out of the smallest corner of his eye, he caught sight of the color of her skin. Nothing, but nothing, will stop a boy dead in his tracks like the sight of a tan line when seeing one wasn't expected. Yep, stopped him dead in his tracks. He silently backed away from her door. From the shadows, he could plainly see his step-sister hugging a pillow and vocalizing. He could not make out what was being said, but she seemed irritated. She tossed the pillow aside and seemed frustrated. He continued to watch and could make out... one hand jammed down against her crotch and the other was fondling one of her budding tits. His mouth dropped open when he saw her slide her hand into her waistband. She was masturbating! This was too much. His sister was rubbing one out. Then he heard it... she called a name. His name. Not to him, she was calling to someone with his name, someone also named "Alex".
This was too much, he couldn't stand watching her any longer, it was too intense. Becky wasn't a blood relative, they were both 18 but she was 3 months younger so she was his kid sister nonetheless and there is only so much a stand-up guy should be asked to take and Alex was feeling a near uncontrollable urge to walk in and "lend her a hand." She was the first live, in-person, old-enough-to-have-tits girl he had ever seen naked. He wasn't a prude; he just wasn't that popular.