Henry found Kirstin sitting on the edge of their parents' bed. "What are you doing in here?" he asked.
"Getting ready to fulfill a fantasy." Kirstin bounced on the bed. "It's a water bed. I've been fucked a lot, but never on a water bed. And look up." She pointed to the mirror mounted on the ceiling. "I think my mom and your dad are kinkier than we ever realized."
"Could be, but I'd rather not speculate on our parents' sex lives."
"Well, we know they have sex, but I guess you're right." Kirstin stood and shimmied out of her shorts. "So what do you think? Going to fuck me here, or what?"
"It's our parents' bed."
"That's the point. It's exciting to think about what might happen if we got caught, isn't it?" She lay down, spread-eagled. "Come on, big brother, this is your last chance to taste my pussy in this house, at least until our parents decide to have another weekend away."
Henry couldn't resist. He bent and licked her slit, enjoying the moans he brought from her. Kirstin squirmed as he tongue-fucked her opening. "Damn, Henry, why didn't you do that to me before?"
"A man has to keep some secrets."
He sucked her clit into his mouth. "Fuck, Henry!" Kirstin cried.
Eating pussy was something Henry had always loved, and he flattered himself that he was good at it. From his stepsister's reaction, he was right about his assessment of his abilities. She had one of the sweetest pussies he'd ever eaten, and he prolonged it, bringing her to the edge several times before he finally let her cum.
"Fuck, yes!" Kirstin shouted. "Oh, my god, Henry, that's the hardest I've cum yet! We're definitely going to keep doing this after this weekend. There's no way I can give up someone who eats me that well."
"Of course we're going to keep doing it," Henry said. "We'll just have to find somewhere else to do it. Like my apartment."
"I've never even seen your apartment."
"Maybe I'll take you over there tomorrow, if you don't have other plans."
"I was planning to fuck you. We were going to spend the weekend, remember? Just because Mom and your dad are coming home early doesn't mean we have to give up those plans."
"Sounds good to me."