A/N: Yep, this is Zim/Purple, and this is mpreg. No, I don't think mpreg is hot or cute or anything like that; I think it's an interesting idea to explore. Hence, as much as possible, I'm gonna keep everyone in character, follow canon, and retain the attitude and tone of the show. So, Zim is still a (lovable) buffoon, Purple still hates Zim—at least at the beginning—and the Irkens are still genitalia-free and born in tubes. Well, they are most of the time. Don't expect any mushy-gushiness on the part of either Zim or Purple, and certainly no one going "omg I get to be a mommy!" That'd be... scary.

Enjoy the fic, and please remember to review! I can't tell whether or not anybody's enjoying this unless you say so. Thank you!

Disclaimer: I don't own Invader Zim. This might be a good thing, actually.

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In Short Supply

Roller Coasters

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From Dib's notes, nine months ago: Possibly learned something new today about Zim's culture. There are ads up all over the school for the annual Valentine's Day Dance. Apparently it's a big deal for the eighth graders but they act like jerks to seventh graders at the dance, so I'm not going. Probably won't go next year, either. But that's not the point.

I've never seen Zim as shocked as when he saw those posters and someone explained to him what they were for. Later in the day someone asked him to go to the dance with her, and Zim actually looked sick. He's not even attempting to act like a human over this dance. He's really grossed out about it.

After lunch I heard him saying something to that Keef guy who keeps following him about "this horrible school's Valentine orgy." I think he was talking about the dance. Maybe "dancing" means something different on his planet than it does here? Note: follow up on this later. Could be important. Or funny.

xxx

Zim couldn't currently remember how he had ended up dancing with one of the Almighty Tallest and wasn't quite in any condition to think about it.

After all, it had been a long, long time since Zim had last danced. Due to his height he wasn't really attractive, and his personality wasn't particularly winning—not that he himself was aware of this, of course. All he knew was that for some reason Irkens were rather put-off by his advances. On most days he believed that this was because his sheer awesomeness simply intimidated whomever he was trying to seduce, but today... well.

Today had been odd.

Not in the least because of the all-consuming oddity that was the Tallest Purple actually coming to Earth in order to dance with Zim. Everything came back to that. Not that he was complaining, exactly. Oh, no. This would probably be the highlight of any Irken's life.

Zim wished he could just relax and enjoy it, then. Sure, it was awkward—the size difference, the complete lack of prior intimacy between himself and the Tallest Purple, the fact that neither really liked each other personally even if Zim respected Purple as his Tallest—but that shouldn't keep him from enjoying the dance itself, right?

Besides, he reminded himself, he was doing his duty for the Irken Empire.

As of today, this was the only duty Zim had left.

xxx

Zim should have guessed that morning that the day was going to be a strange one, when the demonic-teacher-overlord of his homeroom class had announced that they were doing something fun that day. That in itself should have been a major hint that something wasn't right.

"As much as it pains me to do this," Ms. Airy (who was just as terrifying as Ms. Bitters had been) had said, "the school district insists we keep morale high enough that less than ten percent of the student body attempts suicide over the school year. So save your despair for summer break."

Zim had looked down at his desk, back stiff, horrified. He hadn't been able to believe his hearing for a moment. What indecency! He would surely have to report this to the Tallest... delicately. There were some topics that were simply too vulgar to discuss under any circumstances—topics so taboo that not even Irken news broadcasts would discuss them. For this teacher-fiend to mention the worst of them, suicide, so flippantly in front of so many people... What revolting kind of planet was this? The humans were even filthier beasts than Zim had thought.

"In any case," Ms. Airy continued, "you get a day off. The whole eighth grade's going to the Poop World theme park, trip sponsored by Poop Cola, the great patrons of our school district who want you to rot your teeth out blah blah get out of my classroom."

With that dismissal, the classroom erupted in a cacophony of cheers. Fortunately, Zim had long since gotten over the bewilderment he used to have every time his human classmates spontaneously started being noisy. When they stampeded out the door, Zim leaped out of his seat and let himself be pushed outside.

Somehow, as the students were shoving their way through the halls and out of the school, Dib had navigated his way over to Zim. "Gee, Zim, you don't look very happy!" Dib said with exaggerated surprise. "What's the matter? Aren't you excited about the theme park?" He lowered his voice. "Do you know what a theme park is, Zim?"

"Of course! Who doesn't?" Zim haughtily lied. "I am thrilled to be going to this park place."

"Oh yeah? If you know so well, then tell me what it is," Dib said.

"I don't need to waste my time explaining a theme park to an ignorant monkey like you," Zim snapped. Dib smirked wickedly and slid back into the crowd of students, moving away—but not far away.

Zim wished he could still keep an eye on Dib. Two years ago, when he had first landed on Earth, it would have been a simple task to monitor him through the crowd. But now... well, in seventh grade they had moved from elementary school to junior high (or "Joonier Hi," as the sign outside said), and the only difference Zim could detect was that he couldn't track Dib anymore because everyone was taller than him. Everyone.

Zim hated this planet.

He endured the bus ride to this theme park by sitting in the back beside his math teacher, Mr. Mudd, who slept through the whole ride. (Mr. Mudd considered Zim his star pupil. Zim considered Mr. Mudd a nincompoop.) Luckily, upon their arrival, a zitty male who seemed to be a park slave appeared and explained the purpose of the theme park. With all the Poop Cola propaganda taken out of the speech, Zim concluded that the theme park was a vast entertainment facility, used to stimulate the microscopic attention spans of humans. The students were supposed to stick together, so the park slave started leading them towards a ride while the teachers loosely surrounded the students, keeping track of them.

The ride they were heading to was called "bumper cars," which sounded incredibly violent. Zim perked up a bit. That sounded good. He was already a genius pilot; surely on a two-dimensional battlefield he could easily slaughter any competition. He'd have a great victory to report to the Tal—

Zim froze in his tracks, almost making a few other students stumble into him, and stared up, gaping. What was that massive thing looming over the park? A wavy rail, held up by the flimsiest of metal structures, with some sort of vehicle rocketing precariously along the rail. Zim could hear the screams of humans trapped in the vehicle. Surely this was a torture device. But what was it doing in an entertainment facility?

"Whatcha looking at, Zimmo?"

Zim glanced sideways at Mr. Mudd, who had stopped walking with the other students. "Uh..."

Mr. Mudd chuckled. "Not scared of roller coasters, are you, Zim?"

"Of course I'm not," he said automatically.

"Are you sure?" Mr. Mudd said, giving him a concerned look (an evil look, Zim thought). "There's nothing wrong with being scared every once in a while, you know."

"Ha! I could ride these roller coasters all day without flinching!" Zim said. To avoid further interrogation, he added, "Now, if you'll excuse me, I must rejoin my friends," and stalked off. There were, in fact, three or four human students who claimed Zim was their friend. He used them as convenient and ignored them the rest of the time. He usually couldn't remember their names. Except that human with red hair that used to be such an annoyance, although he was tolerable now that Zim had given him those permanent brain implants... Kif, that was it.

So, this theme park wasn't purely entertainment. It was a way humans asserted their rank on their social ladder, by displaying combat prowess in the bumper cars or fearlessness on the roller coaster. It was an opportunity for Zim to prove his superiority.

"Hey, alien."

Oh, wonderful. Dib had apparently hung back from the main group. He strolled towards Zim, smirking. "You've never gone on the roller coaster before, have you?"

"I... what's it to you?!" Zim said, glaring up at Dib.

Dib's smile widened. "Don't you know, Zim? All humans like roller coasters."

"You think you can fool Zim with such a stupid lie? I know very well that not all of you meat-bags enjoy that ride," he said. How could anyone enjoy a torture device?

Dib's smirk faded. "What's that supposed to mean?" he asked. "Maybe you are scared."

"Never," Zim snarled.

"Good." Dib leaned over, sticking his ugly nose in Zim's face. "Then how about a challenge? We'll both go on the roller coaster. The first to chicken out... or die, is the loser."

Die? Then death was possible on these vehicles? Unless, of course, this was some misguided attempt at intimidation. Yes! That must have been what it was. After all, the Dib-stink was too cowardly to risk his life. Zim shot a glance at the distant rail and at the quickly leaving group of eighth graders. "You're on."

xxx

Zim understood torture strategies quite well. He had studied them, briefly—just as he had studied advanced piloting, biophysics, interplanetary combat, electromagnetic systems, physiology, espionage, A.I. programming, and the fine art of frying stuff.

One of the most well known torture strategies was that of suspense. The anticipation of future pain was enough torture by itself to make the strongest minds crack. Clearly, humans utilized this strategy to its fullest.

That was the only explanation Zim could think of for why he had been in line for the roller coaster for nearly an hour.

"How much longer is it?" Zim demanded for the thousandth time.

"I don't know, Zim," Dib muttered between gritted teeth. Zim hoped this was a sign that he was about to crack under the pressure and admit defeat. "We'll get there when we get there."

"That's circular reasoning, y'know," Zim pointed out. "When else would we get there? Sometimes you humans baffle even me with your stupidity, and I'm used to you."

Dib shot Zim an exasperated glare, and then returned to trying to ignore him, leaning on his elbows on the wooden railing that surrounded the line for the ride. After a moment, he mused to himself, "That phrase is pretty dumb..."

The roller coaster carts pulled back into place, and the attendant unlatched the safety bars so the riders could get out and wobble their ways to the exit. "Next!" he shouted.

Zim glanced at the carts, and then counted the number of people in front of him. He was up next. "Finally!" He shoved past the rest of the line to get to the attendant faster. "Hey you! Park slave!" he shouted up at him. "I demand a place in your filthy torture-cart! Zim does not fear your coasters!"

The attendant gave Zim a baffled look. "Er... wait a sec," he said, hurrying over to his control booth and looking for something on the floor.

"A sec? I don't have a sec to waste! What's taking so long?" Zim looked at the closest cart. Maybe if he made a run for it...

The attendant returned with a long ruler, which he stood up beside Zim. At the top was a miniature wooden cut-out of Poop Dawg, with his arm extended horizontally and a word bubble that said "You gotta be this wit' it to be jammin' on da trip, yo." Um. Was that supposed to make sense to humans?

"Sorry," the attendant said, pointing at the word bubble. "You're too short."

"No I'm not!" Zim said, and then paused. "Too short for what?"

"The ride. You've got to be this tall to get on," the attendant said, pointing at Poop Dawg's outstretched arm. The line was a quarter of a foot over Zim's head. "I can't let you on."

Zim stared at the ruler. "I... I... you what?"

The attendant sighed impatiently. "The exit's over there," he said, pointing at a set of double doors with peeling grey paint. "I've got to load the others."

Zim was still staring dumbly at the Poop Dawg. He had failed this quest to prove his superiority to the humans. He hadn't been able to ride the roller coaster. He was... inferior.

"No! Wait!" Zim clung to the attendant's pant leg as he tried to walk to the next in line. "Let me on! I can conquer this roller coaster blindfolded. Just let me in. I'll ride it like it's never been ridden before!"

"Sorry?" the attendant said uncomfortable. "Rules are rules, little guy." He tried to shake Zim off.

Zim flinched. Little guy?

"Maybe if you come back in a year, after you've grown some." The attendant gave Zim a critical look. "Or maybe three years."

Zim finally let go. Then this, this was a permanent defeat. Zim would never grow. "But..."

The attendant ignored him and started loading other, taller riders into the carts. As Dib passed, he looked annoyed, but managed a snicker when he saw Zim. "See you after the ride, shorty." Zim noticed dully that Poop Dawg's arm only went up to Dib's nose.

That was too much. Publicly humiliated, Zim walked out of the exit, into the theme park, and headed towards the way out with his head low. In his mind, the laughs of the humans having fun were jeers directed at him.

Zim forced himself to hold his head high and march with his back straight, not looking at anyone or anything. An Invader must demonstrate the ideals of all Irkens at all times, including never, ever showing pain.

He headed home among the mocking laughter of those taller than him, trying to maintain his dignity and trying to tell himself that he didn't care about what everyone around him thought of his height—they'd see what he could do soon enough. Soon enough.

It felt just like home again.

xxx

Zim entered his base to discover no less than two hundred enchiladas painstakingly laid on the floor, like a carpet. He gaped at them for a moment, and managed to collect himself enough to shout, "GIR!"

For a moment, nothing; then Zim noticed that some of the enchiladas were moving. He was on the verge of ordering the computer incinerate the unholy cheesy beast, when he realized that it was just Gir. Coated in enchiladas.

"Gir? What is this—"

"Shhh!" Gir hissed. "They're sleeping."

Zim stared at the mass of food. Knowing Gir and his tendency to do very stupid things, it was probably beef. Zim was allergic to beef. "Gir, why is this room coated with food from Mexico?"

"They didn't have a home!" Gir said. "They need me!"

"Fascinating." Zim extended his Pak legs to walk over the mess. "Computer!"

"Whaaat?"

"Clean out this mess! I want this room spotless within ten degrees," he said, to Gir's wail of agony.

"Uh, that's about... an hour, right?" the computer said uncertainly.

This was what Zim got for steadily replacing parts of his system with human technology; a computer that couldn't tell Irken time and that liked to display the Blue Screen of Death when it was in a bad mood. "Yes, computer. It's a little over an hour."

"Right."

Zim retracted his legs to climb into the kitchen toilet and take the lift down to the subterranean levels of the base. "I don't want to be bothered for the rest of the day except in case of an emergency," he said. "Understood?"

"Sure."

"I expect more respect than that, computer!" Zim said as he stepped out of the lift. "Do you understand?"

"Uh... sure."

"Rrgh!" Zim kicked at the nearest computer consol. "Shut up!" He stomped into the spherical recharge chamber, slamming the button to shut the door with enough force to make it shoot out a few sparks.

"Sheesh. Somebody's touchy today," the computer muttered.

In the recharge chamber, Zim settled back in the chair (which was much too large for him; recharge chambers were designed to be one-size-fits-all), adjusted his position to let the plugs on the chair attach to his Pak, and used the connection to turn on the computer screen in front of the chair.

Recharge chambers were designed so that an Irken could refuel their Pak while mentally wired-in to a computer, so they wouldn't have to lose contact with the outside world; however, Zim kept the screen on for less than a minute before he turned it off. He didn't want contact with the outside. He wanted to stay in here until he could convince himself that the entire day had been an irrelevant accident full of strangeness, and that the worst of it was over. Zim needed to recover his pride.

There was a reason why he had wanted so badly to be an Invader, even when there were so many other jobs that offered equal honor in the Empire; Frylord, Royal Inventor, Communication or Navigation Technician on the Massive. Zim was quite certain, in the way he was ridiculously certain about absolutely everything he did, that he would have been more than qualified for any of these positions. Except in one aspect. Height.

The Irken Military was the only exception to the rule. Everyone had a chance at glory. Everyone could become a hero—and even if some would never receive recognition for their heroism, if the Empire refused to reward them simply because they were lacking in some way, the fact would remain that they gave some great service to the Empire that nobody could take back. Becoming an Invader, however, actually offered that recognition. No matter what your height was, if you conquered a planet, then that planet was yours.

That was why Zim had devoted his life to becoming an Invader. The Tallest actually needed short Irkens for the job, because depending on the native population of a world, a larger Irken might not always blend in. This was the only way Zim could demonstrate to Irk what he believed to be the sheer amazingness of his abilities.

He didn't need to be reminded on the very world he was intending to conquer that, no matter what he did, he would still be tiny.

Zim had almost convinced himself that the entire day was just a fluke, when the day decided to get stranger.

The computer screen turned itself on. "Uh, Zim? You have—"

"Computer!" Zim snapped. "I told you not to bother me unless there's an emergency!"

"That's what I'm saying!" the computer protested. "There's an Irken Spittle Runner in orbit and it's hailing you. It wants to land."

"What?" Zim unplugged his Pak from the chair, hit the button to open the recharge chamber, and ran to the nearest lift. "Why didn't you tell me? Who is it? Anyone of rank?"

"Uh, yeah. It's—"

"Tell them they can land in ten minutes! I need to prepare myself," Zim said.

"Actually," the computer said tentatively, "he already landed. He ordered me to let him in."

"What?!"

"I told you he's high-ranked."

Zim stared at the speaker in disbelief. "You stupid—"

"What was I supposed to do?" the computer demanded. "Say no to the Tallest?"

"Of course! Never do anything without my..." Zim blinked. "Who?"

The lift door opened, revealing the Spittle Runner and the Irken climbing out of it. Zim froze in the lift, staring as the Almighty Tallest Purple surveyed the hangar of his base, disdainfully glancing at Zim's Voot Cruiser.

The Tallest caught sight of Zim. "Oh," he said. "Hi."

Zim attempted to collect himself and took a few trembling steps forward. "M-my Tallest. I—" the lift door slammed shut at his heels and he jumped. Hastily saluting, he said, "It's an honor to have you here, sir!" You have no idea—"

"Yes, yes, you're humbled in my presence and will remember this day until you die," Purple said flatly. "Look, this isn't a social visit, and I promise you, I do not want to be here. So if you can just—"

"This is a social visit?" Zim said excitedly. "I... well, of course, I fully understand why you would want to spend time with someone as amazing as myself, my Tallest, but it is still an honor to—"

"No! Are you even listening to me?" Purple made an annoyed noise, rubbing his forehead with his knuckles. Zim noticed for the first time that he wasn't in his Tallest uniform; all his armor and his hover-belt were gone, leaving only a sleeveless, striped white shirt, and his ankle-length skirt. Sure seemed like something someone would do on a social visit. "This is business, Zim. A—new mission for you, okay?"

Zim's eyes widened. "A new mission? What... kind of mission?"

Purple sighed again, and screwed his eyes shut. In a strained voice, he said, "I need... you to... bear my offspring."

Zim stared at Purple. "Huh?"

Purple opened one eye. "Lay eggs, Zim," he said, his voice even more pained. "Have smeets."

Zim nodded, very slowly. "Okaaay," he said. "So..."

"So?" Purple prompted.

"So," Zim said, "who are you really, and what have you done with the real Tallest Purple?"

"Oh, come on!" Purple said. "I do not need this, Zim."

"Mm-hmm." Zim drew a laser and aimed it at his Tallest's head. Purple took a step back, alarmed. "Start talking, imposter."

Purple groaned. "I knew this was going to be a bad day."

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