On Kate's last night off Delilah and I had to behave. Dena had come home and Kate's sister came over to have dinner with us and visit awhile.
At one point my sister-in-law got up to use the restroom and I made an excuse to go to my office to look for something. I knew I'd probably not see anything if she was just using the toilet, but it's just so addictive, anything I see them do in their privacy excites me. I didn't see anything on the cam at first and then the top of her head appeared in the bottom corner.
I was so intent on staring at the screen to see if she would do anything, I nearly jumped out of my skin when a hand rested on my shoulder from behind. "Del! Jesus you nearly gave me a heart attack! What are you doing? Kate's going to get suspicious that we all excused ourselves from the living room."
"Well that's no fair little Bro. What....you come in here for all the fun and I have to stand lookout for you? Let me see." she said as she stepped around me and took my phone from my hand.
I looked at what was on the screen and saw that Kate's sister was standing at the mirror. She leaned way in to it and was picking something from her teeth. When she was satisfied she had gotten it, she straightened back up and turned sideways to the mirror and looked at herself. She stood on her tiptoes while watching her side profile in the mirror. She turned and did the same with the other side. She then smoothed something out on her shorts and reached up to her heavy looking breasts and jogged them around a bit. Satisfied everything looked good she walked out of the bathroom.
I took my phone back from Delilah "Now we have to go back in at different times or they'll wonder what's up."
"Oh chill out Bro, maybe I just wanted to come to your office to check out the certificates and awards on your walls." Delilah harped as she walked around my office looking at the framed documents on the walls. "Impressive little Bro, such a professional man turns a woman on." she had made the circuit of my office and now stood in front of me.
Delilah placed her hand on my chest and bent her knees and let her hand slide down my body to the waist band of my shorts where she stopped. She then stood back up and walked out of my office saying out loud as she went through the door "Very impressive brother, I'm so proud of all your achievements."
I rolled my eyes and walked out behind her and went back to the living room.
The next day we all went to the lake for a picnic. We had a good time but it was mostly uneventful. At one point though, while Kate and Dena were packing things up to leave, Delilah asked me to take her picture. I walked with her to a bench that was beside an ornamental fountain. She gave me her phone and went to sit on the bench. She got her pose just right and said "Go ahead."
I snapped off a couple shots and saw Delilah uncross her legs and let them fall open. She was wearing a loose flowy sun dress and now I could clearly see she had no panties on!
"Make sure you take plenty so I can pick the good ones." Delilah said with her mischievous look. She feined that she was straightening her dress out and held it up so that I had a perfect view of her bare legs and spread pussy.
I turned to see what Kate and Dena were doing and saw that they had gotten everything packed and put in the car and were walking towards us. I walked over and sat next to Delilah on the bench and told Kate to take a couple pictures of me with my sister. I didn't really care about the pictures, I needed to sit down a minute to hide the full blown erection my sister had just caused.
We got home around dark and Kate went straight in to get ready for work. I had a few legitimate things to do in my office while Delilah and Dena chatted in the den. Kate peeked in a bit later to say goodnight and off to work she went.
I was in my bedroom to put some night clothes on when Delilah came in and hurried over to me. She pulled me down to sit on the edge of the bed and said "Get your phone out, Dena went to take a shower."
I quickly fumbled my phone out and opened the cam app. There was Dena standing at the sink wiping her makeup off. Good, we hadn't missed anything yet. We both watched as Dena pulled her shirt over her head and revealed her bra covered tits. The bra cups were low cut and her juicy tits overflowed the top a bit. We both watched as her tits jostled around with her movements.
Next Dena started to pull her tight bottoms down. She struggled a bit, pushing each side down alternately, her panties rolling down with them getting tangled. As she was struggling to step out of her pants I noticed one tit had come out of her bra enough to see the upper part of her areola. I felt Delilah lean forward getting closer to the phone screen. She was loving this.
Dena had escaped her pants and now reached behind to unclasp her bra and let her heavy breasts roll out. She stood in front of the mirror, rubbing her tits, turning this way and that examining her nude body. As she stepped into the shower I felt Delilah's hand creep over to my leg and move up to my already stiff cock. "This is really turning me on lil Bro."
She rubbed my cock through my shorts for a minute then stood up and turned to me. She kneeled and pulled my shorts down to my ankles. My cock sprang out of my shorts and made an audible slap against my belly. Delilah leaned forward and began rubbing all around my prick, occasionally cupping my balls in her hand. My sister then took my cock into her mouth and swirled her tongue while working up some saliva for lube. She started bobbing up and down on me, taking my whole length all the way inside each time she went down. She worked my cock like this for a while and suddenly stopped to look up at me "Don't forget the camera." she said.
I looked at my phone as she said this and Dena was just stepping out of the shower. I stared at my stepdaughter's naked body as my sister expertly worked my cock in and out of her throat. I was in pure ecstasy. Dena finished toweling off and began to put her night clothes on. "Del, she's almost done. We've got to stop or she'll see us for sure."
Delilah just kept bobbing up and down and then paused, "Let her watch." she managed to say with her mouth full.