Make his sister aware of the swap

Having his sister's vagina was a blast so far for Zack. But how would his sister cope with it? Of course, as of now, things should - according to the manual - seem to everyone like they have always been this way. Speaking of, he had an idea he wanted to check.

Zack stepped off his bed and took a look at his boxers. They were still plain, white boxers, however, as he already discovered, the were slightly shorter and made for a flat crotch. He went over to his drawer to verify his idea: And he was right. His boxers were now boxers designed for women.

"Of course, if things have always been like this, I wouldn't get myself boxers for males but for females. And... wow, so I even have some panties.", he said to no one in particular, holding a pair of blue panties in his hands.

"I assume I was just curious about how it's like to wear them. Interesting."

Tossing back the panties and closing the drawer, he put on his boxers and pants and unlocked the door. Stepping outside, he went straight for his sister's room, noticing how walking also felt different with the void between his tights.

"That must mean she should have male boxers... or at least regular male underwear. As expected, she is still not in her room..."

He checked on her underwear drawers, careful not to be caught, and was right with his assumption. She had a mix of boxers and other male underwear.

"Heh... that device... that's... incredible. And even scary. How did Nathan get his hands on that? Why did he give it to me? And did he know of it's powers...?", Zack pondered. Smiling to himself, he knew: "But one thing is for sure, it DID spice my life up quite a bit. I should be freaking out right now... if not because of having a vagina between my legs, then out of joy..."

He went out of his sister's room, back to his own to get the device, and then to the living room, where his sister seemed to get up in the moment he entered. Quickly deciding that it would be fun to play a 'small prank' on his sister, he chose to make her aware of the situation.

He took out the device and and flipped the 'REALITY ALTERATION' switch, and sat on the seat next to his sister, whom just sat up.

"Hey bro... how long did I sleep?", she said softly, still a bit groggy. Zack couldn't help but grin like crazy at her. In just a moment, she would freak out over having a dick between her legs.

"Oh dunno, probably an hour or two.", he answered, anticipating.

"Oh well, I'm off to the toilet.", she dryly said, scratching her balls on the way.

Zack sat there in disbelief. Didn't he flip the switch to 'OFF'? He checked once again: He did. What did he do wrong?

He rushed into his room and took out the manual. After 5 minutes of reading, he calmed down.

"Ahhh, that's how it is. And I feared it had a malfunction. Haha. So either 'ON' or 'OFF' only counts for when making an actual swap, I see. And... you can make people aware of everything caused by this despite reality alteration by pressing this button here, thinking about them, and then the swap button... very interesting. That's even better than what I wanted. Hehehe... this could be fun."

He flipped back the reality alteration switch and went to the toilet, noticing that his sister is still inside. She seemed to be washing hands.

"Alright, prepare, sis...", he whispered to himself as he pressed that specific button, thought about his sister, and then activated the swap button...

"Wha... that's... oh my god...", his sister said. Zack was listening behind the door, chuckling to himself, but being surprised at how calm she was. He expected more screaming and "OH MY GOD I HAVE A PENIS!!"

He notice how quiet it had gotten behind the door, but he was really curious about what she did, so he acted like he wanted to use the bathroom and entered.

"Hey sis, are you-", Zack said, cutting himself off as he saw his sister sitting on the toilet, playing with his old member and inspecting it at the same time. As she saw her brother entering and seeing what she did, she froze.

"I-I-It's not what it looks like!! I... I mean...!", she whimpered, desperately trying to justify this situation. Zack had to control himself to not break out laughing, but kind of felt bad, and thought about telling her what's going on, however, be decided against it. Not yet. Seeing his cute sister being shocked by having his penis, desperately trying to make sense of the situation, was just way too amusing.

Zack put up a serious face. "Then what is it? Explain!", he said in a shocked tone.

"I... this... uh...", she took a deep breath before continuing, "Okay, so. I just went to the toilet, finished my business, and wanted to wash hands. Suddenly, this... my penis felt like it was totally new to me and so I was shocked. I mean, imagine you would suddenly have a vagina..."

Zack looked down at himself and gave his sister a quizzical glare, trying hard to keep up the charade.

"Eh... oh... uhm... right, imagine waking up with... a penis.", she said, sounding more and more off, the more she said. She seemed to be thinking about something. Zack decided to keep looking at her, curious about what she thought.

"Hey, Zack, don't you think it's kind of weird how we are, like, the only humans to be born with the genitals of the opposite gender? And we are siblings... isn't that suspicious?", she said, massaging her package a bit, which was kind of irritating but also hot to watch. Which then again was a bit disgusting to himself, as he wasn't into dick girls. Or ****.

Zack couldn't help it but laugh. His sister was quite stunned.

"What...?"

"Oh, Sara, I'm sorry, this is just too funny, oh man, I can't! Give me a second."

"What's going on?! Why are you laughing...?", she whined, extremely confused.

"Okay, okay, lemme explain, dear sister. I was fucking around with you. Long story short, a got hold of a device that can swap body parts and alter reality to make everything like it has always been like that. And it can make specific people aware of everything I do with the remote. While you were on toilet, I made you immune to the reality alteration. Understand?", Zack said, still with a smug smile on his face.

His sister took a few seconds to take that in.

"Hold on. I get you. I understand... it makes sense. I mean, it doesn't, but I'm the girl with a penis so I believe you. But that means...", she looked sharply at Zack, "...you swapped our genitals?"

Zack didn't except her to understand everything so quick, he blushed and looked away in embarassment.

"Uh, yeah, I mean, sorry, I just, I dunno, I wanted to test it, you know-", he explained, but was cut off by his sister suddenly hugging him.

"W-What? Why?", Zack stammered.

"Hehehe... now you're the shocked one, aren't you?", Sara said, releasing him. "Well, the thing is, I kinda was into this kind of stuff. You know, I always wondered what it's like to have a dick to be honest. I forgot about it, but as you just made me aware of it, I remembered, and well, I won't question how or why any further, but instead just thank you. Thank you Zack!", she blurted out, chuckling at him.

"Hold up... that's a lot to take in for me aswell... are you serious? And you are fine with telling me that?"

"Yeah, sure, I mean you have gave me your Zack junior. After having experienced that, what's the big deal?"

"Oh, well, I guess you are right..."

"Say, why did you make me aware of this?"

Slightly thrown off by the question, he answered: "I just... thought I could get a funny reaction out of it and then again make you unaware. But... things turned out unexpectedly... I guess I won't make you unaware again now..."

"You better not, little bro! Hehehe... this is really interesting. Did you do anything else with the device so far?"

"No, just swapped our genitals and made you aware of it..."

"And... did you have a fun time with my pussy?", she said, in a slightly seductive tone. Zack couldn't help but blush. But he figured that it wouldn't make sense to keep such things a secret from his sister any further, so he gave in.

"Yes... yes I had fun with it, and it was amazing. In fact, just like you, I wondered what it's like to have... y'know, female parts. That's quite a coincidence you felt the same way, the other way around...", he said, going all out, which wasn't planned, but didn't really bother him anymore.

"Oh wow! Now I get it. That's truly fortunate! So you don't mind me keeping your member for a bit longer? I would like to have some fun of myself too, after all."

"Uh, yeah, sure..."

"And then let's have some fun together with that thing! What do you say?? Zack and Sara and their swapping adventures! Doesn't that sound great?!", she said enthusiastically, like a little kid. Zack was even more thrown off by that, but didn't dislike her idea.

"Hmm... sounds interesting, I think we can give it a shot. This is really an unexpected turn of events... I believe we will have fun."

"Oh yes we definitely will! Tell me though... this just came to my mind while thinking about the device... how often can you swap? And... can you swap whatever you want? Like, a right arm with a left arm?"

"As far as I know, I can swap as much as I want, and yeah, such swaps should also be possible."

"Oh boy, this will be sooo much fun! But for now, excuse me please. I need to investigate this lil' fella a bit further.", she said, running off to her room.