“Woah... it’s so... big.” Liam gasped, staring at his bare, pale ass in the mirror. Giving it a squeeze and watching it wobble, he was hypnotized by the view of his step-sister’s plump, naked butt. “I never knew Holly was hiding such a precious booty...”

Liam’s new stepfather had just moved into his home and alongside him was Holly, his new stepsister who was around the same age. From the start the twonever got along and were constantly arguing. Holly was a spoiled princess who was used to getting her way, while Liam was a typical high school student who couldn't stand her constant whining. It was due to all this arguing that his stepfather, who made a living as an inventor, decided to test out his latest design: he thought that if he swapped their bodies for a few days, the pair would eventually develop a better understanding of each other’s struggles. Unfortunately, Liam had other plans...

Planning to make fun of Holly by stripping her body butt naked and mooning her, he took a photo and planned to send it to her as an ultimate the ‘fuck you’. However, as he began pulling up his pants his phone began buzzing like crazy. Picking it up he realized in horror that he’d made a horrible mistake - instead of an angry message from his sis he’d accidentally posted the photo to his friend group’s chat! All of them were talking about how lucky Liam was to have gotten such a great photo. Some were even encouraging to get more, saying that he should ‘try and get lucky with her’.

Realizing it was easier to fess up now rather than later, he reluctantly walked to her room to apologize. Upon opening the door however he was in for another shock: Holly in his old male body had her pants around her ankles, stroking his old cock as she watched porn on her laptop. Liam tried to close the door but it was too late, and she had already rapidly began trying to cover herself up. “Uhh... I was just... doing my homework...” she stuttered, suddenly a lot less like her obnoxious self.

Still averting his eyes, Liam bit his lip as he tried to ignore the heat between his legs. “N-No... it’s fine. Just do whatever you need to do, I know how horny that body gets sometimes...” a few seconds later he could already hear Holly jerking off again. Snatching a look he was appalled by the way she used both hands to awkwardly stroke the length of the dick. “No, you idiot, that’s not how you do it... let me show you.” he lectured. Moving over towards the bed he took the cock between his soft, delicate fingers and began to stroke like he usually did, the rhythm coming natural to him as he heard Holly’s deep masculine moans. Soon after Holly was now groping her female brother's braless breasts, teasing his nipples and causing Liam to moan in pleasure too. After several tense minutes he heard footsteps move towards the door as he felt Holly’s cock tense up, and knowing that finding his old body covered in cum would get them grounded forever, he did the first thing that came to mind: brushing the hair from his face and wrapping his mouth around the pulsating dick, his mouth filling with salty, warm seed.

“How are you two going?” Said Liam’s stepdad as he cracked open the door, finding the two laying on bed next to each other hanging out. “Getting along? Glad to see my experiment has worked out. Perhaps I can change you back sooner rather than later, hmm?”

His mouth still full of cum Liam was unable to answer, so Holly took the initiative. “No, dad, I think it’s okay. Can we stay in these bodies for a few more days? I think I still have more lessons to learn...” Under the sheets she gave Liam’s soft rump a squeeze, cementing their new, lust-fuelled, secret relationship.