The reunion lasted for a couple of more days and then Sebastian returned home. He barely talked to Cassidy after the afternoon they spent together. Sebastian thought she didn't want anyone to suspect. He had no idea how to tell his sister. He thought about calling her but it was easier to delay it. When he got back her home he unpacked and then went over to Kathryn's room. He had to tell her.

Kathryn was lying in bed reading a magazine. She asked him about the last couple of days of the reunion which she missed. Sebastian told her about those last couple of days and then took a deep breath and said:

"There is something I must tell you, sis."

"What is it?"

"Well It's Cassidy…she knows we had sex there, she set up cameras there and she saw us."

"She saw…us together, Sebastian?"

"Yes, she did. She came over to my room the next day and…"

"And what?!"

"She told me about the cameras and we ended up having sex."

"You're kidding!"

"That's not the whole story she's also blackmailing me. She threatened to tell about you and me unless I give her half of my Mer Fashion shares."

"She blackmailed you and you still let her fuck you?!"

"You know me sis, I couldn't say no to her, she's…"

"She's that hot you had sex with her even though she was blackmailing you?"

"Well..yeah..I.."

Kathryn looked at him and giggled. "It's OK, brother, don't worry about it."

"Huh?". He asked.

Kathryn turned on the TV. Sebastian was amazed. What he saw was a video of him and Cassidy having sex. "What the hell is going on here sis?", he demanded to know.

Kathryn got out of bed and approached him. "You see, I found the cameras in my room when we got there, there were also cameras in your room. Cassidy suspected we were sleeping together and installed the cameras."

"Why didn't you tell me?"

"Because when we had sex I needed that to be believable, I needed her to think we weren't aware of the cameras. She had the cameras removed the next morning and then I installed my cameras in your room."

Sebastian was dumbfounded. "I don't understand, she has the video of us…"

"I had her tapes replaced with blank tapes. She has no proof of anything. The tape of you and Cassidy together was delivered to me this morning"

"I don't…"

"I bribed her maid, OK? Right now she thinks she has evidence of me fucking my brother but in fact I have evidence of her fucking her cousin. I have all the power now, brother."

"Then why did you ask me…"

"I needed to know you were still loyal to me", she said and kissed him, "And that you loved me."

"Oh God of course I love you sis", he said and they kissed. It wasn't long before she started to unbutton his shirt."

"Well you had a busy week, didn't you?", Kathryn asked as they were fondling each other, "Fucking your sister then fucking your cousin."

"Yeah we're a happy fuckin' family", he said and they both laughed. Within a moment they were both naked and in bed. Kathryn was on top."

"Wow sis, your plan was brilliant, you're fuckin' brilliant sis!", Sebastian said.

"Yeah I am. I'm a fuckin' brilliant sis, and right now I'm a fuckin' sis, fuckin' her hot brother", she replied as she began to thrust her body against his. As she was doing that Sebastian said: "You know sis, technically I won the bet."

"Oh you won fair and square, we're…Oh God that feels good", she said as the pace of the thrusts was picking up."

"So what's the plan sis? Are you oh God, planning to blackmail Cass…Cassidy now?" He was struggling to speak as each thrust caused him to shiver in pleasure.

"No. I want her to think…of fuck yeah…she got us, give her the shares…"

Sebastian felt her fingernails scratching his nipples and knew she was nearing climax.

"That's smart sis."

"You know I watched you and Cass..oh God yeah…on tape..you were trying really hard there…"

"Of course sis, I wanted her to…want to fuck me again…"

As he said there she climaxed. Sebastian couldn't hold it any longer and soon followed her. They smiled at each other as they were catching their breaths.

"Cassidy mentioned something about coming here later this summer, she'll want to…get together."

"That's perfect. Let her think her little plan is working."

"Are you OK with me and her, you know…"

"Oh please, brother, we'll be fine. I need you to fuck her real good, we'll practice", she said as they giggled.

"You probably have to update your little notebook, don't you?"

"Oh yes, there's a very interesting chapter I have to add." They giggled again.

"You know sis", Sebastian said, "You took a big risk there. What if your plan didn't work?"

"Oh I knew it would work."

"How could you be so sure?"

"I noticed how Cassidy looked at you. She's been craving you for years, but it was too risky for her. You would have the upper hand as far as she was concerned. After she had us on tape there wasn't any risk, she could finally fuck you."

"So you were losing the bet on purpose?"

"Yeah…I thought about it. As long as we're living in this house we can't just stop. We'd be craving it the whole time, we'd be resenting each other. We've gone too far to stop now."

"And what about if we want to see other people?"

"If one of us will want to pursue a serious relationship with someone else then we'll talk. I think we will find a way to understand and respect each other."

"I still don't get what's the big deal with those shares. The company is going bust."

"It's a test. Cassidy needs to know she can blackmail you. Once you give her those shares she'll move on to bigger things."

"Ok", he replied, realizing she was right. "I noticed something, sis", he added, "Was it your intention that Cassidy would think that we were fucking for the first time?"

"Yes it was. I realized it would be hard to pull off. That day when I returned home and I pretended to end things with you…I thought that would convince her. I thought it would be better for us if she thought that."

"Brilliant sis! Wow what and idiot Cassidy is thinking this was out first time!" They both laughed loudly.

"How many time did we do it anyway?", Kathryn asked laughing.

"I don't know", Sebastian replied", last year of high school and a couple of years since we've started college. There are like fifty weeks in a year and we had like two or three sessions every week."

"And sometimes more than once per session", Kathryn said.

"Yeah", he replied, "So like 500 times."

"500 times! Wow! Kathryn replied."

"Well 501 now", Sebastian said giggling. They gazed into each other's eyes and laughed. After a few seconds they leaned towards each other and kissed.

"I love you, brother", Kathryn whispered in his ear as he rolled on top of her.

"I love you too", he whispered back. He was thrilled. His intense sexual relationship with his sister was back on and now another sexual relationship with his cousin was forming. Intense pleasure shivered his body every time he thrusted his cock into Kathryn's body. Kathryn was again moaning and panting. "Can I call you Cassidy, sis?", he moaned.

"Hell yeah!", she replied.