The Chimera are a parasitic alien species of unconfirmed origin that colonised several worlds some 60 millions years ago and came to Earth at that time, when the Chimera or their creators were at war with another alien race. It is unknown what the outcome of this war was, but it left many artifacts behind on Earth and possibly shattered the Chimeran home planet. One of these artifacts is buried in Chicago. The object is neither Chimeran nor human technology, and is believed to be belong to the unknown race that had fought against the Chimera. Another such object is believed to have been at the Chicxulub Crater. Although artefacts still remain on Earht and possibly other nearby worlds, the Chimera are beleived to be extinct.
In a different timeline from our own, they were brought back to life in Siberia shortly after the Tunguska event starting The human forces initially believe the Chimera to be the result of a biological experiment gone wrong, but with the Chimeras' advanced technologies such as weather control, energy weapons, and force fields, it became obvious that the Chimera are extraterrestrial in origin. The Chimeran army expanded by infecting humans with a mutagenic virus that caused its victims to fall into a coma, then slowly transform into Chimera while inside cocoons. Intelligence reports speculated that more than one human body is needed for the larger strains of Chimera. The Chimera built conversion centers across their territory to both speed up this process, and create new breeds of Chimeran creatures. Large, jellyfish-like creatures, called Carriers, brought infected humans that have fallen into comas to these conversion centers. The Cimera soon started leaving the cocoons right in the cities where they were infected.
The American experiment named Project Abraham had Americans tested the chimeran virus on human subjects, and tried to inhibit the virus in some way. Some were alos tested with an ancient source of the virus coming from the Ancient Chimera that came to Earth more than 60 million years old.
Noted physical characteristics of the Chimera include having between two to six bright yellow eyes, greatly varied anatomies, and grayish-green skin. Their metabolism is another one of their more interesting aspects, as it is twelve times that of a normal human being. This enhanced metabolism grants them extraordinary regeneration abilities, speed, and strength.
The side effect of this trait is that their bodies tend to overheat, which literally cooks them from the inside out. In order to counteract this effect, Chimeran soldiers have artificial cooling devices implanted on their backs in order to survive. This suggests that Chimera are not being created under ideal conditions. The Chimera tend to thrive in very cold temperatures and there have been successful attempts by the Chimera to alter the Earth's climate to suit their needs. As a direct result, temperatures in certain locations such as London have been reduced to sub-zero temperatures, resulting in those areas being frozen during July. The biology of the Chimera is detailed even further in SRPA files XX458199 and DNA548781PA.
The genetic make-up of the Chimeran virus appears to have been specifically designed to attack and modify human genes, suggesting that there is something more to the Chimera than is already known. Chimera devour their own kind, usually their wounded or dead.
The Chimera are led by creatures called Angels (large, flying monsters with multiple limbs emanating from their backs and extending toward the front around their heads) which possess a telepathic link to the Chimeran soldiers. Without this link, the Chimera under that Angel's control rapidly begin to die off in a matter of days, or even minutes.
Angels take shelter in areas known as Chimeran towers which are massive spire like structures that are often hundreds of feet tall. It turns out that the towers are excavated rather than constructed as was originally believed. Something radical happened in the Gulf of Mexico 60 million year ago, which incapacitated all the towers that are scattered around the world. It is presumed that the Chicxulub event is linked to this due to a mysterious object being described by intel and the location in the Gulf.
Notes: Although looking quite different externally and behavorially, the Chimera share some characteristics, mainly the ability to genetically adapt themselves to other species to take them over, with the Kimera seen in the Earth Final Conflict TV series.