Mark decided to go show the modified portal device to his friend/classmate Nikki. He knew she ran her own portal streams fairly often and was knowledgeable about how they work. If he was to have someone assist his testing, her experience would come in handy. However Mark wasn't exactly sure what she DID with her portal receiver during streams, since Nikki always stopped the stream when someone had arrived.

He had known Nikki for years, she was one of those people that would always end up in his class every year. She was kind of a tomboy and she played volleyball a lot, most of the time she hung out with Mark like she was one of his guy friends. They'd all egg each other on to do stupid stunts, and out of the group of them Nikki told the dirtiest jokes. She liked to tease Mark a lot an push his buttons for her own personal entertainment. Sometimes she'd step on him, or use him as her replacement volleyball towel, or even catch him by surprise with a fart to the face.

It was all in good fun. Mark probably would have minded it more if puberty hadn't treated Nikki so well. She had grown two generous D-cup sized breasts and full wide hips. Nikki exercised and played volleyball constantly so her body was thin, toned and sporty. Above all else she had an amazing round ass. Occasionally she would joke around and sit on Mark's seat while he was already occupying it, calling him "her chair". Mark would laugh along and try to hide his joy, just the feeling of her big butt sitting on his legs was amazing.

There were a few moments in Mark's life where he had almost asked Nikki out. In the end his romantic feelings were pushed to the side and he decided not to ruin the good friendship that they had. That didn't matter much anymore, he has his girlfriend Megan now, but there were times where he would wonder...

He knew she would be thrilled with his invention so he left to go show it to her.

----

"You did WHAT?!" shouted Nikki, shocked and ecstatic at the same time.

Mark was sitting in her bedroom holding out the portal device for her to see. Nikki practically had stars in her eyes after Mark explained the situation. She couldn't believe he had been working with a portal production company to created a modified device.

"I said, I modified it. The company was so impressed with my work that they gave me my own device." Mark said, beaming with pride.

"And you said it can make people grow instead of shrink right? And that you could move the portals while they're active?"

"Yup!"

"Dude, with that kind of power you could almost do anything..." Nikki pressed her thumb to the bottom of her chin. She looked up at Mark giving him a serious glance. "Are you sure this isn't your evil villain backstory or something?"

There it was, Nikki's hilarious acting skills. Mark laughed off her joke.

"No no no no, nothing like that... ... or is it?" The two of them chuckled.

Nikki got up from her bed and began pacing back and forth in her bedroom. She was thinking of different ways to use the device and voicing her thoughts out loud.

"We could move the larger portal over whoever we want and shrink them! We could just portal to school instead of taking transit! You could make me into a giant! I'd be the first person to ever climb Mount Everest in a single step!"

"It'd be too cold." Mark said flatly.

"Shut up. Maybe we could charge people to use it? Nah, too risky. Can it do stuff with time? Could we travel back to the past? Could it start playing time backwards, like in reverse?"

Mark felt an odd chill. "I don't think so. I've tinkered with adding time buttons, see those blue ones there on the side? But they don't really work properly yet..."

Nikki pouted. "Maybe we could... wait, this thing can pass through any receiver right?"

"Yeah, and?"

Nikki shuddered. "I don't like the idea of that. What if someone hacks into my receiver and comes into my room without me knowing?"

"But no one else has a modified device. Just me." Mark said.

"Yeah but we don't know that for sure. I'm taking the batteries out of my receiver just in case. Someone across the globe might have made a modified device just like you. They could hack into my receiver, shrink themselves, and molest my tender body while I sleep!"

She did an overdramatic fake sob at that last part, crossing her arms over her ample chest. Obviously she wasn't as worried as her words would have him believe, but Mark could understand where she was coming from. It'd be scary to be a young girl in a world where people could just teleport inside your bedroom.

Nikki ducked down under her computer desk to find her receiver. It was somewhere between the mess of wires and cords where she had dropped it the day before. It took Mark a second to notice but when Nikki hunched down under her desk her ass stuck up in the air, pointed right at him. Her hips wiggled sexily back and forth as she absentmindedly looked for her receiver. Mark couldn't help but stare, her butt looked so good in those yoga pants.

"Got it!" she shouted, returning with the receiver. Mark nearly jumped out of his seat, pretending he was staring anywhere but at her body.

Nikki popped the batteries out of the receiver. "There, done. Okay Mark, let's start testing this thing out." she said with gusto.

Mark turned the device on. "Okay, now for the first test I think it'd be best to-" then he stopped and looked at her. She had her arm outstretched as if she was waiting for Mark to pass the device to her.

"What?"

"I want to try it out," Nikki said matter of factly. "to see if it can really hack into receivers and streams."

"No way! I made it, so obviously I'm going to use it first." Mark refused.

"Awww, come on! I'll give it right back!"

"No."

"I'll give you five dollars."

"No."

"Ten?"

"Nuh-uh."

"Twenty? Fifty?"

She was getting bothersome. Even still Mark wouldn't give in. After all the work he put into making the device he wanted to be the first one to use it.

"Nope." he said.

"Hmmmm... okay then. How about..."

Nikki hopped herself up on Mark's lap and put an arm around his shoulder. He could feel her warm skin through her leggings. He knew what she was doing. If Nikki couldn't get Mark to see things her way she would always try to use her feminine charms to convince him. Sadly for Mark, it usually worked.

"How about you let me try the device first and I'll let you touch any part of my body you want." she said, giving her cutest manipulative smile.

Mark didn't say anything. Nikki giggled.

"Come on man! I know you want to. Don't think I didn't see you checking out my ass earlier."

Mark's face turned red.

"Wha-? How did you-?" With one look at the smirk on her face her realized she was just bluffing and he had completely given himself away.

"Ha ha so you admit it! Not that I blame you, my ass is pretty sexy." she said her words confidently but Mark could've sworn he saw her blushing too. "I'll give you three minutes and you can touch my ass all you want. Or maybe you wanna touch my boobs instead? Well?"

Mark looked back at her. She was pressing her big breasts together with her arms to entice him. They looked so soft dammit. He sighed.

"...Fine."

"YEEEEEEE!! Yes!" Nikki cheered.

She leapt off Mark's lap and jumped for joy, knocking him off his chair. Mark stood back up and reluctantly handed her the portal device. While he did so, he said to her:

"You said I have three minutes to touch whatever I want right? In that case, I'm going to touch your..."