Sebastian thrusted his perfect ass harder and harder. It was a Friday afternoon, time for Kathryn's and his weekly date. He took a sneak peak at the clock next to the bed. It was quarter to six. 15 minutes until the date was up. He felt Kathryn's hard nipples against hist chest. He was about to cum for the 3rd time since they started fucking at 3 o'clock pm.

A few months earlier, Kathryn and him came to realize that the whole Annette saga was really a way to try to resist the great sexual tension between them. So they abandoned their stupid bet and focused on themselves. The first time they had sex they spent an entire weekend in bed unleashing their lust for each other. That was the best weekend in Sebastian's life. But then they realized they had to set some rules and according to the rules Friday, 3pm to 6 pm was his times. He could put it anywhere he wanted, tell her to wear what he wanted and Kathryn had to oblige. Weekdays were hers. There were weeks in which she invited him to her room every night and there were weeks in which he hardly even saw her at all. Weekends were off and they were free to date other people. On 10 pm Sunday night the deal was back on and if Kathryn was horny Sebastian had to sleep with her. The rules only applied for hours in which they were both at home. That week he hardly even saw her. Usually on Friday afternoons he would fuck her for about an hour then rest for a little while and fuck her for another hour. Then they would lie down together cuddled and naked until 6 pm and then they would usually not even see each other for the rest of the weekend unless there eas some family function which they both had to attend.. But since they haven't done it since the previous Friday Sebastian decied that twice was not enough this time.

"Did you fuck that blonde last Saturday?" She suddenly said as she clutched his ass. That was another rule. They had to be completely honest with each other about who they were dating and having sex with.

"Yes", he said as he kissed her neck.

"Good", she said as she suddenly started to moan more heavily.

God…you fuck so good in weeks you fuck others…so good…

He could now feel her fingernails scratching his ass and he started to thrust his cock as fast as he could.

"Oh God"..she moaned heavily…"Oh Sebastian oh yesss…"

He couldn't hold it any longer. He came quietly with a soft moan and a second later she pushed him off and immediately got up and started to dress. She looked at the clock next to the bed.

"Right on time. 3 orgasms in 3 hours. Not bad for Kathryn. Thank you brother."

"Thank you", he said, still struggling to catch his breath. "By the way I will not be available on Monday night."

That was another rule. They had to alert each other at least 3 days in advance if one of them would not be available for sex. If Kathryn would not be available Friday she would have to alert him by Tuesday at the latest and they would schedule a day in which she would make him up to him. As for Sebastain, the rule was there was only one day a week in which he could alert her he would not be available. On the Monday of the third week of their arrangement Sebastian told her he planned on inviting some friends over for poker on Wednesday. She said: "Fine, but if I wanna fuck Wednesday you call it off and send them home. " When he tried to argue she said: "Look, rules are rules. If you wanna you can schedule for Thursday and then it will be Ok because that's three days from now. But if I want you naked in my bed on Wednesday night and you don't show up then the whole deal is off and we'll never ever have sex again." When Wednesday night came up and Sebastian was setting up food and refreshments, Kathryn came up to him and said she wanted to have sex that night. "Look", she said, "These are the rules, you are at home, you didn't give me your three days in advance not available notice. So, according to the rules you have to get your ass into my bed in 10 minutes." " Please", he said. "just one exception.."

"No exceptions! Right now or the deal is off. You know that cute guy James who's been calling me? I think he'll be very happy to receive a phone call for me asking him if he's free tonight. And then tomorrow morning I'll be telling you how he fucked me all night long and how I sucked his huge cock. And the morning after that. And the morning after. And you'd be so jealous but you'll never have me again because the deal is off." At that moment Sebastian got a huge erection. Hardest he has ever been and wanted her so bad. He called his friends and called off the poker night. After the first time he came that night she told him: "Don't you just love it when I demand sex from you like that?" She smiled at him and he smiled back at her. They ended up doing it six times that night and the sex that night was even better than their first night together. Ever since he has been very careful about the rules.

"Very well Sebastian. I'm going out with some friends Sunday night. I'll be back around midnight. Wait for me in the shower."

"Ok", he said. Still gasping.

She leaned over and kissed him on the chick.

"Thanks brother, I'll see you then."

And she did.