An Open Expirement

BY : RandomJaz
Category: +G through L > Invader Zim
Dragon prints: 1549
Disclaimer: I do not own Invader Zim or any of its characters,nor do I profit from the creation of this fanfiction.

I never thought I'd see the day Gaz showed me any interest.

She stood in the doorway of my bedroom, eyes locked on to mine. Her impassive face unimpressed per usual. Her mouth was drawn in a line, teeth probably touching inside her mouth. She looked like that whenever she walked in on me, but unlike her normal routine instead of walking away with some monotone remark, she stayed.

My glasses were off, placed somewhere on my desk. Zim lay on his stomach, his ass in the air as my dick was buried so deeply in to him his cheeks squished under the weight of my pelvis. He was panting hard, having been fucked in to the mattress a few seconds ago. My tall lanky body outsized him fairly. The creak of my door caught both of our attentions as we rattled the bed springs and I stopped to see who had entered my room.

It wasn't the first time she forgot to knock, she'd walked in on us before. The recurring event struck me as oddly repetitive and I wondered if maybe she actually hadn't forgotten to knock. It seemed as if she purposely skipped it. She'd walked in so many times, headphones in ears and videogame in hand, that it was almost normal.

She would normally say whatever she had to tell me, usually that she needed a ride. Or that Dad would be gone for another couple of days and our allowances and grocery money were already wired to our bank accounts. But this time she said nothing, standing there with her headphones and game console missing. Her brown eyes were unconcerned, blinking normally with steady slips of her eyelids. They were focused on us.

Her eyes were always uninterested, matching her cold temperament. I was used to it, oh boy was I used to it. She often ignored me unless it was otherwise convenient for her. But she really surprised me this time, standing there as if there was something interesting to see. She still had on her beat up converse sneakers, and her eyeliner was smudged under the lower lids of her eye. Her purple lipstick was worn off in the center of her lips, probably from whatever she'd eaten at lunch.

She'd gotten home from school probably minutes earlier and I realized it was much too early for her to be home. The highschool let out at two, there was no way it was two. Zim came over as soon as she left for school, he'd only been here a few hours. It had to be twelve o' clock at best.

"Why are you home?"

"Early release" she responded, unmoving from the door frame. "Thought you had class."

"It's Tuesday"

Gaz Knew my schedule. Monday, Wednesday and Friday I was at the community college all morning, then I'd come home. Usually with Zim. She wasn't the type to forget things. She knew I was home. If not from the shere fact it was Tuesday, Zim's erotic screaming carried through the door of my room when we were alone.

"Oh" Her answer was lazy, almost like she said it as an afterthought. Like she hadn't planned on replying at all.

Zim's green skin darkened around the swollen slopes of his ass and face and he groaned, a very very low keening sound. His large ruby eyes were looking at the foot of my bed and I kept my eyes to the right, watching my sister. At this point my nudity didn't phase her, or the position I was in. She flicked her eyes down to Zim, noting his distressed noise.

"What's wrong with him? He looks like he's in pain."

"He's in heat" I answered her simply.

She blinked once, looking at Zim as he groaned underneath me. He didn't care that he was being looked at, he didn't care in the least. He just wanted me to relieve him of the discomfort he felt, the insufferable heat in his loins. Gaz being there didn't effect him, he just didn't like that her presence stopped what I had been doing to him.

"You trying to knock him up or something?" Her question was so casual, voice only slightly less raspy than years before.

"Of course not."

I inched back out of Zim just a bit to show her the rubber strapped on to me but thought better of it and stopped. I didn't need to show her, I didn't need to tell her. She walked in on me unannounced, I could just throw her out and have every reason to do it. I didn't though.

"You should wear a condom then" she suggested bluntly, shrugging like she'd told me something as simple as what she wanted for dinner. "He can get pregnant, or at least that what your log said"

I ignored the fact that she'd gone through my studies, reading my reports on Zim. I didn't care in the least. She did as she pleased when she pleased, always going through my experiment findings and reading up on whatever I'd discovered about the alien beneath me.

"Did you need something?" I asked her finally, confused about her extended stay which was dragging on. By now she would have been long gone. "I'm in the middle of something"

"I can see that"

And there it was again, the look in her eye. The subtle intrigue of what she took in before her. I gave her a questioning look, unsure of what she was up to. She stared at me and she leaned off the doorway a little, and I anticipated the click of my door shutting as I leaned back up from my knees to carry on with Zim.

I froze as I heard her shoes scuffing the carpet in my room, followed by the click of her closing the door. Turning back to her I was faced with her apathetic face, expression emotionless but she looked at me expectantly. It was now obvious what was going on, and I didn't know where to begin on how to feel about it.

"What are you doing?" I acted dumb anyways.

She shrugged, her shoulders coming up to brush the large flips of her shoulder length hair. It bounced, the strands shifting stiffly with whatever sticky hair product she had in it. I didn't question her further and she walked past my bed and sat down at my desk chair, the piece of furniture turned to face Zim and I.

"Just observing" she told us, crossing one leg over the other. Striped knee high socks leading up to a purple skater skirt and a black long sleeved shirt.

"This isn't an observation study"

Gaz tapped her foot. Still watching us.

Zim's long skinny fingers scratched at the bed sheets and he pushed back against me, the low keening sound coming from deep in his throat. The muscles where we connected constricted on my still prominent erection, begging for stimulation.

"We're waiting."

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