The First Appearance of the Black Oil

The Black Oil in Piper Maru

The alien virus known as the Black Oil or the Black Cancer first appears in the third season episode "Piper Maru." The Black Oil as it appears in this episode seems to act as a sentient, controlling agent that uses humans as hosts. It is transmitted from person to person, only infecting one host at a time. Its mode of transmission is unclear, as the episode only shows the before and after of infection. The primary indicator of infection with the Black Oil is a cloudy black appearance to the eyes. After the Black Oil has jumped hosts, it leaves a residue of oil, indicating (though perhaps this is only clear in hindsight), that the virus uses oil as a medium for transportation. The Black Oil also can cause intense radiation burns in those exposed to, but not infected by it. Those infected are unharmed by the radiation. It seems that the Black Oil can control this release of radiation, as it can travel in hosts through public spaces without affecting the general population; rather, it emits radiation in controlled, intense bursts. The Black Oil is generally reticent, but is capable of controlling speech, and even understanding humor to an extent, as after Krycek is infected, he tells Mulder he feels "like a new man." The Black Oil can also manipulate its hosts to travel long distances, though its motives remain unclear, aside from that they are somehow related to Mulder's investigation of government conspiracy.

In "Piper Maru" it becomes clear that the Black Oil has existed at least since World War II, though this information is transmitted to the audience through flashback. One striking difference between the flashback and the present expereicnes with the Black Oil is that the men on the ship seem to be infected over time, becoming sick progressively, while the Black Oil radiation in the present seems to produce instant, more intense effects on its victims. While initially there is no reason to doubt Commander Johansen's memories, the Black Oil only appears in the flashback after he makes the decision to lock the commanding officer, who has been infected, below deck. This means that Commander Johansen did not actually witness the appearance of the Black Oil. Is this flashback then to be taken as accurate? Does Commander Johansen imagine that the captain is infected, or is the flashback truthful historically, supplemented by Johansen's narration?