Ben loved his mom on top as it allowed unfettered, constant contact with her epic t**s. There was also something about her being on top that revealed her desire for him. She controlled the depth and pace when she rode him. Ben mentally took notes while she straddled his c**k, eager to learn all he could from her movements. He could tell how aroused she was, or whether she wanted a deep orgasm or more of a c******l one.
How she looked at him while she was on top was also very telling. Did she stare into his eyes? Was she looking at his body? Were her eyes closed? He had discovered that her eyes revealed her mood, her feelings for him.
In the warm light of the nightside lamp, Ben considered her face as she made love to him. He adored her features; the perfection of her cheek bones, the elf
