Chimeras were first created through the use of t-Virus as a vector for splicing arthropod DNA into a newly-formed human embryo, then inserting it into the uterus of a female subject. All Chimera are clones of the first prototypes deemed a success; as such, they are all human-fly hybrids which are born within a day, and take only 2–4 days to reach adulthood.[excerpt 1]
Chimera posses powerful limbs ending with sharp claws; with these they are able to hook themselves onto ceiling protrusions such as grates and pipes. This allows them to hunt pray from above, outside their plane of vision, with their thin bodies also fitting through air ducts. They are in fact stronger than the Hunter Alpha also created by Dr. Birkin's team in the early 1980s, though their intelligence was considerably lower and made them a poor choice of weapon.[excerpt 2] Further observed traits of the Chimera are that they are incapable of flight and that their bodies dissolve upon death. They also appear to be asexual, as they grow maggots on their bodies.
Chimera typically curl their bodies while swinging on ceilings as a means of protection. When on the ground, however, they will stand up and stretch their arms out to appear larger. Their standard attack method is to slash enemies on the ground or, if hanging on the ceiling, attempt to rip their head off. They have high endurance, and can withstand close hits from a shotgun or grenade launcher.[excerpt 3]