Trill is a cool, temperate world in the Trill sector of the United Federation of Planets. It lies somewhat closer to Cardassia Prime and Zenkath than it is to Earth. The planet has a blue-green sky and purple oceans. Trill has a higher than usual frequency of tectonic activity, likely the product of two large moons. Days are 31 hours long and there are 319.5 Trill days in each year. The planet itself is rich in metals and ores due to the tectonic activity.

It is home to a pair of sentient lifeforms. A bipedal humanoid descended from marsupials known as the Trill and a small, long lived subterranean dwelling lifeform resembling a conical serpent referred to as the symbionts. The two species are capable of entering in a symbiotic co-existence. Once joined they are mutually dependent after only 93 hours. The host can no longer survive without the symbiont. The symbiont during its lifetime can take many different hosts and retains the memories of all of them. When joined successfully the pair operate as a single consciousness much like networked computers. Joined improperly the symbiont can completely overwhelm its host. The symbiont eventually returns to the pools permanently to evolve into the next phase of its lifecycle, known as the Annuated.

The first joining occurred in Trill’s pre-history, more than 23,000 years ago, the memories of which may still exist deep underground in the most ancient of evolved symbionts. As Trill culture evolved more stable joinings, the symbionts long lives led to a more focused societal growth. Trill society was based on achievement in the sciences and treasured knowledge above all else and was marked by a surprising lack of conflict.

The Trill had three different phases of expansion into space. The first some 5,000 years ago led to the establishment of a half dozen colony worlds and was halted by a great tragedy the annihilated the colony world of Kurl and left its surface uninhabitable. The shock to the Trill led to a decline eventually leading to long period of cultural introspection and the remaining Trill worlds gradually lost contact with each other. One of the Trill colonies was later infected with the augment virus and though still Trill is a visually distinctive subspecies with ridged foreheads and lacking the distinctive leopard style spotting of the Traditional Trill.

Two major factors contributed to the rise of Trill technology: the memories of symbionts, and easy access to ores and heavy metals. The symbionts could communicate with the humanoid Trills through Joining, although the ways and means of the first Joining remain shrouded in secrecy by the Trill Symbiosis Commission. Symbionts passed from host to host but retained their memories and friendships, and kept Trill society centered on a long-term view. Geologically, the planet Trill’s heavy tectonic activity led to the formation of quake caverns and eroded tunnels, through which the Trill could easily gain access to deposits of iron, aluminum, and other useful metals. The combination of the two factors led to the rapid rise of technology.

The Trills second foray into space was fueled by an industrial revolution on Trill. Unchecked growth fueled by the invention of gravitic tectonic regulation and weather control led the Trill back out into space and the rediscovery of their colony worlds. The industrial rise however led to an ecological catastrophe that poisoned much of the symbionts’ habitat. Joining became mandatory for the survivors as only the very deepest pools were spared the destruction.

Sweeping controls over the planets ecology were imposed and it would be another five hundred years before regular space travel would resume. Contact with the Vulcans would follow shortly after that, though Trill would remain independent for another few centuries before joining the Federation.

As Trill society grew, their governments adopted a system influenced by the symbionts. The symbiont populations grew much more slowly than the humanoid Trill populations, so many Trills competed to have the right qualifications to be selected as a host. This general competitiveness showed through academic achievement and philosophical development—the symbionts made it clear that they would reject violent individuals who tried to become hosts by force. As a result, all Trill civilization stressed a high level of education and ethical personal responsibility. By the time they had covered all of their planet’s landmasses, the Trill already had a unified world government, a meritocracy run through systems of examinations and scientific appointments. This system was well in place by the time the Trill met the Federation, but matters were still cool between the two powers. Trills valued their independence and their position as a neutral party. Over the exchange of several decades, it became clear that the Federation stood for the same high values that Trill society encouraged—and that the members of the Federation had embraced those values, due to long years of struggle and learning, having worked hard to establish what came naturally to Trill culture. Eventually, the Trill applied for and received Federation membership in one of the fastest turnaround times from application to completion.

Trill is a temperate world much like earth though generally more mountainous and cooler on average. It has about 38% landmass and four major continents, one of which is situated at the southern pole and covered in ice. Another of which comprises more than half of the total landmass of the planet. Since the development of global tectonic and weather control, Trill society has gathered in metropolitan areas of tall domed buildings each surrounded by a few agrarian townships. The majority of the land has been left wild to maintain a balance between technology and nature.

Society revolves around academic success, family prestige is gained through academic and scientific achievement and especially through the awarding of symbionts. The competition for between three to four hundred annual joinings can be intense and only the best and brightest are even considered.

Life on Trill is a showcase of modern convenience with all off the technological achievement of modern Federation science. With strips of nature incorporated into even the largest of Trill cities one is never far from peaceful stretches of green. Outside the cities long stretched of unbroken wilderness beckon to those looking for a bit of a break from modern life.