Arriving at Jan and Dave's house, Jan unlocked the front door silently. As we tiptoed into the living room, we could head moans and grunts coming from the bedroom, even with its door closed.
Jan whispered, "They're clearly still at it. Do we bust right in or get naked first? Make it crystal clear we want to join them?"
"Good idea," I whispered back, beginning to take my office clothes off again as Jan did the same. We lay our clothes over the arm of the couch as we approached the bedroom door. My cock was already getting stiff, just hearing Abby and Dave fucking, when I had not been able to hear them via the spycam feed we had been watching at the hotel.
Jan looked down at my groin and smirked as she ran her fingertips along the shaft. "I'd ask if you're ready, Jack, but I guess this is my answer."
"Let's do it, funny girl," I said back.
Just as we heard Dave cry out that he was cumming, Jan opened the bedroom door with a loud click and we stepped through. "Got room on our bed for two more lovers?" she asked, as both Dave and Abby spun their heads towards the noise. "Or is incest not a group sport?"
After a quickly muttered, "June 4th, again," that made no immediate sense to me, Dave was the first to overcome the shock. "What the fuck, Jan? I thought you were in Denver this week? You lied to me?"
"Oh, spare us the fake indignation, Dave," Jan said. "I only lied about going out of town because you were lying first. Open your eyes, though. If Jack and I were here to rant and rave about the two of you cheating on us, would we both be naked right now? We want to join in."
"What?" Abby asked. "You're not mad?"
Jan sat on the bed and caressed Abby's left arm before answering, "A little mad, but I think I can forgive you, if you stop lying from here on out. I'll tell you the same thing I told Jack, earlier. You are the only woman I would ever be willing to share Dave with - if you'll share Jack with me."
Abby blinked hard, then asked, "You and Jack? When did the two of you start committing incest?"
Jan replied, "In my fantasies? Years ago. For real? About 6 o'clock tonight. When we watched the two of you start up in a 69, Jack got more turned on than he got angry, like I hoped he would. Once his cock was stiff, it was pretty easy to use 'getting even' as an excuse to have him fuck me, just like I fantasized."
"Hang on," Dave said. "You watched us? How?"
I walked over to where I spotted the charger-camera and unplugged it to show them. "This has a camera inside. I loaned it to Jan when she suspected you were having an affair during her business trips. It's WiFi-enabled, so she could watch it from her laptop. When she saw you lighting candles tonight, she called me over to her hotel room downtown to see what happened after that. While I was surprised to see Abby, the turn-on of watching you together erased most of my anger and I admit what turned me on most was the taboo that you're brother and sister. That made it fairly easy to admit that I'm attracted to Jan, too, but would never have made a move on her on my own. After a round together in bed, we decided to come over here while you two were still together and get the air cleared between us."
Jan added, "We wanted to know if the two of you are okay with a foursome or at least allowing some spouse-swapping to go on, without sneaking around. First, though, I want to know what you meant about 'June 4th, again,' when we first came in. What's the 'again' about?"
Abby pulled herself off of Dave's cock, to let Dave sit up against the headboard, while she snuggled against his side, between Dave and Jan. I joined them on the bed, sitting at the foot.
Dave said, "Ten years ago today was the first time Abby and I ever had sex. However, we were almost immediately caught by our mother and I wound up banished to Oregon to keep us apart. It's damned peculiar that we would get caught again on that anniversary."
Abby touched Dave's arm to stop him from telling more of the story and said, "As big as this discovery is, I have even bigger news that I better deliver right now. I just found out today that I'm pregnant, Jack. And I'm not sure which of you is the father."
I'm shamed to say my initial reaction wasn't excitement. "Oh, shit. If we hadn't caught you in the affair, would you have ever told me it wasn't my kid?"
Abby cringed at my tone. "I'm hoping it is yours, since that lowers the genetic risk. The fact of the matter is I just don't know. I had sex with both of you the week I probably conceived. I swear to you that this wasn't something I planned. I was still taking my birth control pills. But, you're right. The baby's paternity would have become part of the incest secret that I've been keeping since before we met. Not just to protect Dave and me from incest charges, but to be sure that you wouldn't reject the baby. The birth certificate needs to have your name on it and Dave can only be its uncle, both officially and practically."
"You think I'd do that?" I asked. "That I would punish a child out of anger at you? Anger I'm not even feeling, to be clear? I get the need for you to keep secrets about incest and Jan and I decided to forgive the lies you told, during the drive here. I just hoped I would be someone you could trust with your secret. Now that it's in the open, you don't have to hide any more. Not from the two of us, at least."
Abby relaxed a little. "Jack, how could I take the risk? Even before you started the police academy, you were a very law and order kind of guy."
I asked, "Since Dave was in Oregon all through college, I assume you didn't repeat it during that time?"
"The wedding was the very first time I'd seen Dave since that day."
"Four years happens to be the statute of limitations in Tennessee for adult incest, so that expired just after you graduated college, before our wedding. If you had told me after it expired, I couldn't have arrested you and I would have forgiven it. Now, I've committed the same crime and I'd be a fool to report all four of us."
"Oh. I didn't know that. Either about the expiration or you forgiving me. At the time it happened, Mom came really close to reporting us before Dad came up with the compromise of sending Dave to Oregon early and refusing him the permission to return until we graduated and one of us was married. I wonder if Dad knew that his leverage over us went away after four years. Before you ask, I did not marry you so that Dave could return. Initially, my plan was to head to Oregon to join Dave as soon as I graduated, even if it meant never seeing my parents again. Falling in love with you changed those plans, totally. But loving you didn't erase my love for Dave."