It was written by staff member Steven Maeda, was directed by Rod Hardy, and forms part of the series' overarching mythology.

Simon de la Cruz, a worker on an oil platform in the Gulf of Mexico, fatally stabs fellow crew member Ed Dell, the radio operator.

Galpex Petroleum, the platform's owner, officially attributes the burns to an explosion, but Mulder suspects the involvement of black oil.

Mulder and Doggett meet Galpex's vice-president, Martin Ortega (Miguel Sandoval), who tells them that the company has discovered a large oil reserve in the Gulf of Mexico.

Doggett and Mulder find proof of black oil and quarantine the platform, but de la Cruz's friend Diego Garza is missing.

When he awakens, Garza, now mentally unstable, cuts his arm to check for the presence of black oil, and warns Doggett in Spanish that "they're coming".

"[6] Maeda complimented the show's producers for deciding to pass the X-Files division over to Doggett, noting that they were "aware of what's going on in the audience's head".

[1][8] Hardy was offered the role after an unknown individual working on The X-Files saw his TBS remake of the film High Noon.

"[10][11] The eighth season was filmed out of order; "Vienen" was the sixteenth episode produced but the eighteenth aired, largely due to Duchovny's availability.

Starting with the eighth season, however, he was allowed to go on several "scouting roadshow[s]" in order to find new and interesting locations that could be written into scripts.

[18] Since her character did not accompany Mulder and Doggett, Anderson had no scenes with Patrick and Duchovny, except for the opening sequence that takes place in Kersh's office.

Production designer Corey Kaplan was tasked with recreating the oil platform's control room, mess hall, and some operational sections, which required "a brilliant piece of synergy between all [of the series'] departments" in order to come together.

The set was made of wood, posing a unique challenge for the art department, as they had to make it look as if the fire was melting steel.

[27] Nine takes were needed for the scene in which the black oil pours out of a worker's eyes, ears, and mouth, as the syrupy mixture would not spill correctly.

[28] Michelle Bush, in her book Myth-X, noted that the oil platform is named "Galpex-Orpheux", a reference to the ancient Greek religious and mythological figure Orpheus, who was a legendary musician, poet, and prophet.

[29] In the episode, Mulder, Doggett, and the two Huecha Indians "wreak havoc" because of their fear, and the "black oil slips back to the underworld".

[29] Douglas Kellner, in his book Media Spectacle, writes that, because the episode alludes to the series' "Super Soldiers" story arc (a plot thread that had previously been referenced in the eighth-season episode "This Is Not Happening" and which would be explored heavily near the end of the show's eighth season and throughout its ninth), it is likely that the title refers to the inevitable onslaught of these alien warriors.

[31] The episode debuted in Ireland and the United Kingdom on June 7 on Sky 1, and was the channel's sixth-most watched program for that week with 0.52 million viewers.

[4] Tom Kessenich, in his book Examinations, gave Vienen a positive review, and wrote, "after watching 'Vienen', I can honestly say that for once of the few times this season, it felt good to be an X-Files fan again".

[36] Kessenich praised the significant development in Mulder and Scully's relationship and the return of the "fourth season version" of the black oil; the 1998 movie had dramatically altered the nature of the substance—infected hosts gestate aliens inside their bodies rather than merely being taken over.

Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, rated the episode two stars out of five and wrote that the installment's return to the black oil mythos seemed "out of date".

"[39] Meghan Deans of Tor.com ultimately concluded that "while 'Vienen' works hard to hit its marks—a classic villain, a battle of dudes—it can’t measure up to all that’s come before it.