A Vat; the somewhat similar Vird clade have feathers, and a more pronounced keel in the chest region
The inhabitants of Mazukata's Holiday were a group of reformed Jansenists who came there in 2289, during the civil wars that eventually destroyed the small Endless Light Confederation. Using a stolen anti-matter drive ship, the Jansenists fled to the only nearby unclaimed habitable planet. Unfortunately, Mazukata's Holiday was uninhabited primarily because of the difficulty of the environment. It orbits a dim main-sequence M0 star, and while this world possesses a breathable atmosphere, abundant water, and primitive life, life on tidally-locked Mazukata's Holiday proved difficult for the colonists.
Living in perpetual day or endless twilight, combined with the winds that continually blew from dayside to nightside produced a host of minor physical and psychological problems for near-baselines who had lived for almost 1,000 years on a cool earth-like world. Combined with minor to moderate allergic reactions that most of the population had from contact with the native life, and the inhabitants were concerned for their long-term survival. Lacking anti-matter to refuel their ship, the Jansenist demarchy voted to begin designing a genome that could prosper on this world and began plans to genetically engineer these adaptations into children conceived here. Unfortunately, research progressed slowly because complete immunity to allergies to the native proteins proved to be closely connected with a number of serious neurological problems.
In 2303, the arrival of the mysterious archailect known as the Vermilion Trader changed everything on this world. The Vermilion Trader travels the outskirts of the inhabited galaxy in a reactionless drive starship almost 2 km in diameter. When it visits a system, it offers its various services to the inhabitants. When it came into orbit around Mazukata's Holiday, it offered to solve all of their genetic engineering problems in return for both temporary ownership of the planet Graymalkin for the next 70 years, and wide discretion in the adaptations is was allowed to make with the colonist's genome.
While many of the Jansenists were eager for it's help, the inhabitants were unwilling to allow the Trader to simultaneously dictate the form of the new tweak, and take possession of the system's most metal-rich body, so the vote was initially negative. As a counter offer, the Vermilion Trader added in a promise of transform viruses so that adults could take on the form it designed, as well as drive cores for 3 reactionless drive starships to be delivered when its 70 year lease on the second planet was complete. A combination of greed and desperation swayed the votes of most citizens and the populace accepted the Vermilion Trader's offer.
In one month, it delivered both the transform viruses and the genetic templates for engineering the next generation of colonists. To the surprise of the entire colony, it had produced two sets of viruses and templates for two completely different tweaks. Both were winged, and possessed a complex limb-doubling that resulted in each arm having two forearms. One set of arms had powerful wings, the other set were slender forearms ending in highly dexterous hands. When adult, both creatures averaged between 1.5 and 1.7 meters tall, with an average mass of between 40 and 55 kg. Their designer's superhuman intellect is readily apparent in the ease with which all of these bionts could fly.
The first template was adapted to life on the planet's dayside. It was slender, lightly built and feathered, but otherwise looked a great deal like a bird-winged human with somewhat prehensile toes. To aid vision, the eyes were sensitive to both visible and visual infrared light, allowing these beings to see clearly in the world's ruddy sun. The second template was covered in light black and gray scales, possessed notably large eyes sensitive to thermal infrared, visual infrared, and visible light, great bat-like wings, and subcutaneous insulation that rendered them highly resistant to cold. Their clawed prehensile toes and slightly exaggerated facial features made some historians compare their appearance to Old Earth decorative gargoyles. Both varieties of tweak were strong, swift flyers, allowing them to easily and safely travel between the various islands of the world's many archipelagos. One of the most unusual features of these two tweaks was that they were cross-fertile. However, hybrids were impossible. Any child born of the two types of tweaks would take on the physical characteristics of its mother. Also, both varieties of tweak could live and work indefinitely in 0-g without problem. These tweaks could fold their wings and easily live and work on even relatively cramped spaceships. However, they needed periodic flights to maintain optimum physical and mental health, so their space ships would need to contain large areas devoted to recreational flying. Also, neither tweak could swim and almost all members of both species would fear immersion in water.
The Vermilion Trader's only other stipulation about its agreement was that no more than 66% of the individuals who used the genetic templates or the transform viruses could adopt one of these two forms. To obtain their reactionless drives both types of tweaks had to be present. Since the colony had agreed to the price, 89% of colonists followed their Jansenist beliefs and had themselves infected with the transform viruses. Within three years, the vast majority of Mazukata's Holiday's 140,000 inhabitants were flying though the skies of this exotic world. Approximately 60% of the colonists choose the bird-winged form, while the remaining 40% became bat-winged fliers.
The advantages of the bat-winged form became quickly apparent, as these tweaks realized the richness of the largely unexplored far twilight and night-bound portions of Mazukata's Holiday. The nightsider's adaptations allowed then to make a far more detailed examination of the separate nightside chemosynthetic ecology built around various volcanic hotspots both on land and under the water. These explorations provided the colonists with a wealth of valuable new biologicals, including several new anagathics and intelligence enhancing drugs.
Meanwhile, orbital telescopes around Mazukata's Holiday noted great changes occurring on Graymalkin. For the first fifteen years, the Vermilion Trader hovered over the planet, sending down small probes that seeded the northern hemisphere with various varieties of construction nanotech. Since their agreement prevented any local spaceships or probes from coming within 2 million km of Graymalkin, observers could not determine the exact nature of this construction. Then, in 2318, a large conversion drive starship entered the system. Failing to respond to or acknowledge any messages from the colonists, it proceeded directly to Graymalkin, where it hovered over the southern hemisphere, and seeded it with its own construction nanotechnology. The world's sulfuric clouds then became so thick that reliable images became impossible. The colonist's theories included everything from two wandering archailects playing a vast board game to some form of transhuman courtship and sexuality. Others wondered if the Vermilion Trader's primary purpose in this whole endeavor was to create two new types of interdependent winged Tweaks and if the entire use of Graymalkin was a ruse to attempt to conceal this fact. The sulfur clouds began clearing in 2372, revealing the rapidly decaying ruins of various kilometer-long constructions. In 2373, the last of these structures fell into rubble and the two ships departed in opposite directions. The only intact structure remaining on the planet was a small building housing three functional displacement drives.
Almost all of the other structures had been reduced to undifferentiated rubble - nanotech disassemblers were used when the lease ended. However, a few structures partially escaped destruction. Most are extremely tall and originally exceeded 2 km in height. All of these remaining structures are partially filled with partially ruined devices of unknown function. These buildings also extend at least 500 m underground (they are build of hyper-strong materials that can withstand Graymalkin's frequent seismic activity). The lower levels connect to long straight tunnels that seem to have connected the various structures. The tunnels range between 0.3 and 10 meters in diameter. Most tunnels have been destroyed and collapsed by disassemblers. However, in two cases, 5 meter in diameter tunnels still connect partially intact structures.
While the inhabitants of Mazukata's Holiday avoided these buildings for more than a century, by 2600 several mining concerns had actually moved into the partial structures. Although many individuals who lived and worked in them reported unusually vivid and confusing dreams, no other atypical phenomena were noted.
Since their voluntary transformation, the inhabitants of Mazukata's Holiday have developed an unusual cooperative culture. Because this particular tweak is exceedingly well adapted to life in zero-g and can fly on any world where gravity x pressure (both measured against Old Earth standard) is 0.35 or less, they have since spread throughout many of the nearby star systems. Today, some live in primarily Jansenist asteroid-mining colonies while others have colonized various small terraformed worlds. Although many colonies outside of their home systems have abandoned Jansenism, the two tweaks are still largely known as Virds and Vats. The one universal characteristic of all of their colonies is none of them consist solely of Virds and Vats, two types of tweak are always found together. Mazukata's Holiday and many other Jansenist worlds are now members of the Sophic League.