Dwarves

The Dwarves stayed while most of the Changed left for Old Earth. The remnants of the Neutral faction that hid in the mountains, out of reach of the lay lines, during the Gene Wars, the Dwarves didn't feel a need to return to a place their ancestors had abandoned. They were already living among the ravages of the planet and surviving; they wanted to keep that strength, not lose it.

They didn't lose their intelligence though. Or their tech. While the newly changed fumbled with the energies coursing through their bodies and the planet's crust after the bombs went off, the Dwarves mined for resources, rebuilt, and turned the world beneath the mountains to their will instead of bending to it. They built the first dragons and drakes, found ways to cage the power crystals in a way that wouldn't make them as susceptible to exploding, and mapped the gravity fluxes of Underhill from below, rather than from above. Eventually, they reconnected with the Changed, and attempted to provide guidance to the new and often young people who occupied edges of the old settlements.

Dwarves were the ones who helped them gain the ships in orbit again. Dwarves built the tools they needed, in trade for pelts and furs and other things they couldn't get below ground. Dwarves, or Neutrals as they were still called at the time, were the ones who put their collective foot down on the topic of any more alterations to either native or imported flora, fauna, or people.

When the Changed found Old Earth and went there to live, Dwarves stayed behind. Visitors would cross back and forth, Changed trickling back to the planet they could never entirely abandon, thanks to the Ambrosia addiction now welded into their very being. Dwarves continued to build arms and armor for the Changed, to find and cultivate Provatio seedlings for the Changed (again, in exchange for trade good from Old Earth, namely food and meat that was untainted by the gene-bombs).

Dwarves are also the ones who restored the ships in orbit to usefulness and started construction of the Jörmungandr. Originally thinking that they could shunt the returning Changed to the ships instead of the surface of the planet, the expanded space stations were modeled on Old Earth topography, biology, and zoology. Later, they were used to for human children who needed to be tested against a version of Underhill before being set free in one of the captive villages. The Changed refused wholesale to live exclusively in the stations, but many did claim small territories on the floating islands, and used them as a base of operations, a bridge of sorts between Underhill proper and Old Earth.

The Dwarves were not without internal strife. It wasn't long before arguments were made over living space, governance, and many other factors. The Neutrals, now Dwarves in truth, were more prolific than the Changed, and outgrew their underground homes faster than anticipated after the wars ended and the planet settled some.

Many wanted to return to the surface, to live in the sun and not hide in caves, depending on lanterns, glowlights, and artificial suns in the huge caverns of the kings. Better to survive the planet face to face, with what weapons and wits they had, than to hide below ground and hope it didn't notice them. Rather than let another war start, the leaders of the dwarves sent those who wanted to leave back to the surface, on the condition they stay there and not come back, even if the planet itself were trying to hunt them.

Another faction resisted the trade agreements with the Changed, and the efforts the dwarves were making to map the planet from below. Better to cut off all contact, and not even give a hint of help to anyone or anything other than themselves. Again, the people were sent away, but they went deeper into the caves and caverns, struck their own mines, and withdrew from the surface world in nearly all ways. They did not, however, stay peaceful, and a number of skirmishes continue to be fought as deep-dwellers meet at cross purposes with the Dwarves and the surface worlders.