A little "harmless" fantasy...

As the hot water washes over you and steam fills the space, you can't help but dwell on Allison. Her pale skin was so creamy: like porcelain lightly flecked with orange glaze here and there for freckles. She was not the buxom, voluptuous knockout her mother was. She was a lithe little spinner, with red dick sucking lips and a tight little pussy. You can't stop these thoughts as they roll in waves through your brain, sending signals to your cock and everywhere in between. She's not your child; she's not even blood-related to you. She just happens to be your niece.
Maybe....maybe she'll persist in her forward behavior, you think to yourself as you lather your cock and stroke it. Maybe, there'll be an opportunity, when its just the two of you, for you to take her nubile body in your arms, and give her the fucking she needs. Educate her a little. Yeah. She needs someone older to teach her what a good....hard...fuck can feel like, and she'd like it too.
All of this serves to speed you towards an inevitable result: jets of white cum hitting the shower wall as you stroke off furiously. It should be Allison's face and tits taking that ****. That last lewd thought crashes home into the guilt-ridden aftermath of your diminishing orgasm. You dirty minded old man. But she started it, didn't she?
When you come down the stairs, Jenna and Karen are in the kitchen. They must have arrived home when you were in the shower.
"Hello, baby..." Jenna smiles, giving you a kiss. You try not to look guilty as you look from her to Karen.
"How was your day, girls?" You can see Allison and Riley in the living room: they're giggling together and shooting looks in your direction. Oh, no.
"It was great. We saw three houses. I really want her to go for...." you let the story of their real estate adventures wash over you as you make eye contact with Allison. Her smile is unsettling.
"...Jack?" you realize you weren't listening, but you think you know the question.
"Oh, he wanted to hit the back nine, and I was tired, so he'll probably be a little..." as you're covering for her, the front door opens, admitting Jack. He looks...sleepy.
"Hey, Jack. How was the back nine?" You hope he takes the cue.
"Oh..it was fine, but I'm beat." He greets his wife, who appears stiff in her affection towards him. "I'm going to shower and take a nap."
"We're going to dinner tonight at a fancy French restaurant, honey." Karen says.
"Sounds great! Somebody wake me when it's time for that..." he climbs the stairs.
The rest of the afternoon and evening passes uneventfully. Riley and Allison are planning to make tacos. Jared hasn't come home yet, but you guess he's working out the details of his upcoming move with his new prospective roommate.
You made reservations at Chat Noir this morning, setting them for 6:45 PM, so at 5:30, you shave, get dressed in a nice pair of slacks, and a deep blue shortsleeve button up shirt. Jenna brushes out her hair and puts on makeup, wearing sheer knee high stockings under a tight dress, with a garter thong and no bra as far as you can tell. Your mouth waters as you watch her dress, and she winks at you as she clasps her nylons.

You head downstairs where Jack and Karen are waiting. The smell of tacos lingers in the air, and the girls are eating by the poolside. Karen's wearing almost the exact same outfit as Jenna, though she's clearly wearing a bustier under her dress.
"You guys ready?"
"Abso-fucking-lutely, Jameson!" Karen pronounces with gusto. Jack looks a little sleepy. Probably still whipped from his encounter today.
Jenna comes down, and the four of you head out, taking an Uber so that you don't have to worry about driving home.