Jean jerks her brother off.

Jean didn’t even think about ignoring Cassandra’s suggestion. The reality that this was her brother, that this was Michael, was present in her head every second, but she couldn’t stop now. She was happy that her swimsuit was so dark, because if it was lighter, someone might have seen the dark patch of wetness spreading from between her legs.

Jeannie reached down into Michael’s shorts. He was already hard. She wrapped her hand around her brother’s raging erection and pulled it up and out from the waistband, though it was still submerged beneath the water.

“Jerk him off,” Cassandra said, three fingers deep inside herself.

Jean was way ahead of her. She had started stroking Michael the second that she had gotten his dick out, and now brother and sister stared each other in the eye as Jean pleasured her brother. She had given plenty of handjobs in her day but it was somehow different when the cock in hand belonged to a sibling— and she didn’t hate it.