Dark Matter is evil energy made of human hate, malice, and anger. Concentrated amounts can create or turn people into Wires, and create monsters. A large amount of it resides on the dark side of the Moon.
Dark Matter ordinarily pours onto the Earth in very small quantities, yet even these are theoretically capable of melting the inner body and replacing the bloodstream. Those who are evil or have weak hearts are more susceptible to undergoing transformations when absorbing the particles, while conversely strong-willed individuals can excise it. During the events of Killer Is Dead, David usurps the moon and amplifies the Dark Matter output to create large amounts of Wires. No matter one's will, with sufficient Dark Matter anyone can be driven instantly insane.