Blair and Stephanie grew up in a household with a divorced mom, who was fairly conservative in her beliefs, being the sister of a minister. Blair was only 16 when his older sister caught him staring at her and her friends, and responded to this "lewdness" with an atypical sisterly gesture- she teased him by flashing him her breasts.
No doubt their mother would have disapproved of this action, but she never learned of it. In any case, Blair's reaction affected Stephanie for years afterward- his cock grew to its erect length of 8 inches. The mere sight of that massive manhood prevented Stephanie from getting too interested in other guys, because, although she liked to go against her strict upbringing by sleeping around, not one of the boys she fucked were able to measure up to her brother cock-wise.
Meanwhile, Blair grew older, left the rural, parochial circles in which he was brought up, and moved to a major city, where he was introduced to the swinging lifestyle by a work buddy at the construction site. He started going to sex clubs, with various girls, as they all required that members attend in the company of a partner.
One day, however, he found a lady crying just outside the club, and he asked her why.
"My boyfriend left me to join a cult! He won't sleep with me anymore, let alone come here, so I am without a swinging partner, as well as short of a boyfriend." she replied.
Her name was Joanna, and Blair, being without a partner himself that night, was only too happy to escort her inside the club for a good time to help soothe the pain. Blair and Joanna thus automatically knew that each other were swingers, so neither of them ever expected or asked for monogamy from the other. After all, the sex club added a sentimental attachment to its erotic appeal for them- it was where they had met.
They got married in just 3 months, and soon had a son, named Oscar, which meant that they could no longer attend the club, since one of them would always have to be home, while the club's rules required members to bring their primary partners.
They each resorted to bars, with the bisexual Joanna going to lesbian joints for girl-girl fun, while Blair stuck to the regular pubs for some straight action. Neither of them had trouble getting laid, since lesbians were all over a sexy redhead like Joanna, and Blair's large dick gave him access to quite a lot of pussy.
When Stephanie joined their household as a guest for a couple of months after her divorce from her abusive husband Roy, Blair and Joanna were pleased to have someone who could help them with Oscar.
Still, they stuck to their rule that Friday night was for Joanna's Sapphic pleasure, while Saturday belonged to Blair. They seldom struck out, especially Blair, who had the advantage of a sizable cock to help him there. The Saturday night of the 2nd week of Steph's stay there should have been no different, but it was very much.
Blair, following the couple's established policy, had fucked Joanna right before he left. Thus he left a satisfied wife soaked with her cum and his, which Stephanie knew well by now, since she had familiarized with herself with the couple's schedule. She was very horny by this point, so it was only natural for her to spy on her sister-in-law's naked body, as the woman lay in utter fatigue from the sound shagging she had just experienced.
Trust Blair to wear his women out, Steph thought. Well, I can use that to my advantage, her mind figured. If I can't do my brother, why not fool with his wife?
She crept into the bedroom, parted Joanna's aching legs, and planted several kisses on her labia, followed by her clitoris. Needless to say, Joanna awoke abruptly at this point, but she didn't yet realize who was munching on her genitalia.
Thinking that Blair must have had one of his rare strike-outs, or else performed a quickie in a restroom, she just let it happen, enjoying it thoroughly. Only when Stephanie's usual moan of feminine pleasure escaped her lips did Jo know that she had inadvertently broken the agreement with Blair by fucking around on the wrong night.
"Who is that?" she exclaimed with a degree of fear, worried since she had a suspicion of who it might be indeed.
"It's Steph, Jo, and don't pretend that you didn't think of that probability. I just wanted to taste Blair's cum for once. I hope you don't judge me for that, dear. I have wanted Blair since I was 19 and he was 16. I flashed him, and saw his erection, which was so large that I have had trouble finding an equal. Even then, most of them would not care for me like Blair does." Stephanie spoke up.
"Steph, thanks to you I am in breach of contract! Blair and I each have our sexual freedom nights, and this was his, not mine! How is he supposed to understand that his incest-minded sister seduced his wife on the wrong night?" Joanna exclaimed angrily.
"Jo, it was my fault, not yours. I violated you, not seduced you! Please, Jo, let's just explain it to Blair together, and see if I can make it up to him somehow." Stephanie responded.
"Oh, I can see what you have in mind, you slut! You want to make it up to him by committing incest with him at last! Well, you're getting your wish, bitch, because we both owe him that much after what I did! If I don't go along with it, I may end up divorced from the best lover I've ever had, and it will be on both of our heads!" Joanna retorted.
