The Tyrant virus allegedly operates similarly to most other RNA viruses, but also has the abilities to reanimate dead tissue, to substantially mutate its host, and to infect nearly any tissue in any type of host. It animates dead tissue by replacing mitochondria in infected cells, thereby providing it with a source of energy to fuel viral creation. It then spreads, eventually reanimating tissue responsible for motor and lower brain functions. By specifically animating certain tissues, most of the body's usual processes, such as heart muscle contraction, are made redundant. However, this process has the drawback of severe necrosis in the host, and produces the distinctive rotted appearance of most BOWs. The mutations are produced when the virus incorporates itself into the host's genetic code and considerably alters it. Creatures with genetic structures different than humans generally show less severe mutations, and usually only increase in size.