The rebels are the only beings, besides humans, that are not infected with an alien virus known as "black oil". (TXF: "The Truth") This concept is only ever implied in The X-Files, most explicitly by Marita Covarrubias in "The Truth". However, such a possibility was supported by Frank Spotnitz when he stated, "The idea is that the black oil [...] was here on Earth, it's been all over the planet, or all over the galaxy, rather. And it infected virtually every life form that there is in the galaxy, except for we on Earth, the humans, and the faceless rebels." ("One Son" audio commentary) The alien rebels avoid infection with the colonizing virus through self-disfigurement. (TXF: "The Truth") They bear facial scarrings, the results of self-mutilation done in order to protect themselves agai