A/N: This started off on AO3 but I've decided to post it here as well. It is entirely the fault of Tumblr and to find out why, search for 'gem egg hell' or visit the 'gem-egg-hell' blog.
Obligatory disclaimer: Steven Universe belongs to Rebecca Sugar/Cartoon Network, I own nothing.
Cladogenesis
They had been sure that the last egg - so much smaller than the others - wouldn't hatch. But it did. And, in retrospect, Jasper supposed that they shouldn't be surprised. After all, she had never thought that she'd mate with a Gem like Peridot on a dismal rainy night on a primitive star-forsaken ball of mud and organic matter when both of them were longing for home. But she had. That had only been the start though; neither of them had even suspected that the smaller Gem could possibly conceive. Such a thing had been rare even before the Kindergartens had removed the necessity to reproduce hundreds of thousands of years ago. Either by accident or design – depending on who you asked – bearing young had been unheard of on Homeworld for as long as Jasper could remember.
So both Jasper and Peridot – whose initial reaction could best have been described as 'revolted terror' – had assumed that the eggs developing within the green Gem would be no more than inert stones produced by some ghostly relic of long-redundant biological processes present in Peridot's genes. Indeed, Jasper had promised the technician – while her hand was being crushed in the surprisingly strong grip of hovering digits – that she would never speak of it again, that it had never happened, that the Homeworld authorities would never, ever know. It would have been an easy enough promise to keep, but then Peridot had discovered that all five of the eggs – even the last one which was much smaller and duller than the others – were registering life signs on her scanners.
Neither of them had known what to do. Peridot was an expert at maintaining a Kindergarten, but had no idea how to deal with Gem eggs. Jasper had a rudimentary knowledge of how the Kindergartens worked but had never really paid much attention; she didn't question where her soldiers came from as long as they were capable of fighting. Acting on half-remembered stories and the vaguest trace of instincts, Peridot had jury-rigged a heat lamp from some parts she had managed to scavenge from the wrecked ship and placed the eggs under it. Jasper had been sure that they needed to be turned regularly and Peridot had accepted that in lieu of not having any better ideas.
All of the eggs were smooth ovoid shapes about the size of a human fist and bright, faintly iridescent, green. The four larger ones had a glossy sheen that the smaller one lacked; instead its surface was matte and slightly pitted. But neither Peridot nor Jasper knew if that was bad, or if it meant that the Gem inside was a different type from the others. Likewise, they had no idea whether the eggs would hatch into peridots, or jaspers, or different Gems entirely. As far as either of them were aware, a Gem's type was set as the seed gem that was planted in the Kindergarten. How it worked with eggs they'd just have to wait and see – assuming that they did actually hatch.
It would have been easy to tip the lot of them into the sea and forget about them, but every time Jasper had considered that option, she'd found herself unable to suggest it to Peridot. And from the occasional furtive looks she'd gotten from the technician, Jasper had wondered if she was having similar thoughts too.
And then the first one had hatched.
Time was hard to measure on the single-sunned, single-mooned planet they were stranded on. It had been a Kindergarten world, so Peridot knew how long it took for a planetary rotation and a solar revolution but equating it to Homeworld time was difficult. Neither of them knew how or even if humans measured time, but since they also had no idea how long it would take for the eggs to hatch – if they even would – then it was a moot point. But after several lunar orbits, one of the eggs had cracked from within and was immediately enveloped in a bright nimbus of light. When it faded the egg had gone and in its place was a miniature Peridot no larger than Jasper's hand. They had stared at it, not sure what to expect. A Kindergarten Gem would have been immediately ready for battle – but then again, a Kindergarten Gem would have been full-sized.
Instead, the tiny Peridot had looked around itself groggily, glanced up at the adult Gems looming overhead, then curled itself into a ball and stopped moving. Jasper had guessed that meant it was dead and given that by all rights it shouldn't have existed, that wasn't surprising. But it didn't disappear into its gem, and according to Peridot's scanners it was still very much alive. Just… dormant? Gems didn't need sleep, but after racking her brains Peridot had surmised that immature Gems – Gemlings – might. Unlike Kindergarten Gems they would need to grow to their full size unaided, and for that it seemed they needed periods of dormancy. According to Peridot, some Kindergarten runts had a tendency to sleep even though they didn't need it, something to do with their stunted development. And before Jasper had been able to give that much thought, the next egg had hatched.
By the time the next day cycle had completed, the four larger eggs had all hatched and four small Peridots were snuggled in a pile under the heat lamp, with the remaining egg at the centre. Maybe it was normal for gemlings to be the same type as the Gem who'd carried them. Jasper certainly didn't have any better ideas, and neither did Peridot for once. The technician had carefully examined each of her miniature doppelgangers with gentle fascination and her actual hands, her usually sour expression – which had only grown more bitter in the time they'd been trapped here – softening as she did. Jasper had never seen her remove any of her limb enhancements before, not even when they had mated. It was obvious that Peridot felt an uncharacteristic warmth towards their offspring, and Jasper didn't question it. The warrior Gem wasn't sure how well she'd be able to deny it if Peridot accused her of concealing similar emotions.
Neither of them had thought the final egg would hatch. They had left it in place beneath the lamp because Peridot's scanners were still picking up lifesigns within it, but as the planet completed rotation after rotation it seemed inevitable that those would eventually fade. Then, as the system's sun rose for the fifth time after the other eggs had hatched, it finally cracked. Jasper had been outside at the time, keeping watch for the Crystal Gems. The cave Peridot had holed up in was deep enough below ground to block any scanners they might have, but that didn't mean they wouldn't find them. Though if Jasper was to be completely honest with herself, those rebels were a secondary concern now. It was Homeworld they had to worry about.
When she'd returned to the cave, Peridot had been hunched over the gemlings with her back to the submerged entrance. She must have heard Jasper surface, but didn't turn around. Jasper's first thought was that the final egg had gone inert and even though she'd expected that she still felt an odd pang of what couldn't possibly be pain in response. But when she'd crouched beside the technician, Jasper immediately saw that the last egg had gone and in its place was a tiny gemling with her own colours. A Jasper type. But not like her, or like its siblings. The Peridot gemlings all looked like miniature versions of their parent, but the proportions of the Jasper were wrong. Its limbs were short and stubby like the stunted Amethyst that the Crystal Gems had taken in, and it was much smaller than the others. A runt.
Kindergartens had produced runts, Jasper knew that. Only about one in a thousand as long as the facility was being properly maintained. But there was only one way to deal with them. Well, unless you were Rose Quartz apparently but that was hardly surprising. Runts were weak by nature and often suffered from other defects – at least that was Homeworld's justification for the regrettable but necessary act of culling them upon creation. One look at Peridot's face had been enough to tell Jasper that the green Gem was thinking along similar lines. And with good reason – one of the duties of a Kindergarten technician was to carry out the culls. No doubt Peridot had done it before… but never like this.
The runt hadn't moved or even opened its eyes yet; instead it was huddled on its side, unmoving. After a moment of consideration, Jasper carefully picked it up, noting that it felt colder than its siblings despite having been beneath the lamp with them. Beside her, Peridot stiffened with a sharp inhalation as if she was about to stop the larger Gem… or just bracing herself for the inevitable. Looking down at the tiny gemling cupped in her hand, not even larger than her palm, Jasper wondered what the easiest way to do this would be. Peridot would know, but Jasper didn't want to ask - this would be hard enough for her already. But it had to be done. It was merciful. The runt wouldn't thrive, it would be a waste of resources, it would never be a warrior and if it didn't die outright it would corrupt and be a danger to its siblings. At least that was what Homeworld's response would have been to a Kindergarten runt, but the one that was running around with the Crystal Gems seemed capable enough and was singularly uncorrupted. Maybe if Jasper left this runt where those sentimental fools would find it then they'd look after it. Then again, since it was technically a Homeworld Gem, maybe they'd just kill it. Better to do it herself. At least then she'd know it had been quick.
Steeling herself, Jasper shifted one callused thumb to the back of the runt's neck. Almost without thinking, she stroked the small thing gently as she gathered her resolve. It would have been much easier to do this if it had been a Kindergarten Gem. Then it would have had a chance to fight back at least. And the third time Jasper hesitated, the gemling runt finally stirred. Rolling onto its back, its eyes slowly opened to glare up at the world that had made it small and weak. It had yellow eyes just like Jasper's, which slowly focused on the warrior Gem whose thumb was now beneath its chin instead of on the nape of its neck. As if it somehow sensed her intent, it made a small squeaky noise that might have been a growl and sank tiny needle-sharp teeth into Jasper's hand.
There was a moment of awkward silence broken only by the runt's muffled sounds of aggression, then Jasper had laughed and the tension in the cave had drained away as she and Peridot both relaxed. Jasper had tried to dislodge the little gemling by shaking her thumb, but it had only sunk its teeth deeper with pugnacious determination. It only let go when set down among its siblings and immediately burrowed its way into the middle of the group where it was warmest, ignoring the drowsy chirps of protest as it made itself comfortable and went to sleep using one of the other gemlings as a pillow.
"We're not on Homeworld," Jasper had said in response to Peridot's unspoken question. "Besides, any Gem that attacks as soon as it opens its eyes is made to be a fighter."
There was a long silence as the two of them looked down at their brood. Peridot's arms were wrapped around herself, her relief at Jasper's actions overshadowed by the realisation that had hit her like a comet when the larger Gem had mentioned Homeworld.
"We… we can't ever go back now, can we?" Peridot asked numbly. She started in surprise as Jasper laid a hand on her shoulder, looking up to see the striped Gem looking down at her with sympathy which clearly showed that Jasper had already realised that fact days ago.
"No." Jasper's voice was firm but uncharacteristically gentle. "Not any more."