Meanwhile, rogue FBI agent Alex Krycek (Nicholas Lea) uses a nanobot infection in Skinner's blood and a vaccine to save Mulder as leverage to make him kill Scully's unborn child.

"Deadalive" was a story milestone for the series, re-introducing Duchovny after his abduction by aliens planning to colonize Earth in the seventh-season finale "Requiem".

[4] In the eighth-season premiere "Within", John Doggett (Robert Patrick) took his place on the X-Files, and worked with Dana Scully (Gillian Anderson) to find Mulder.

Although nearly all were in critical condition, a UFO cult, led by the mysterious Absalom (Judson Scott), was using Jeremiah Smith's (Roy Thinnes) healing powers to treat the abductees.

Meanwhile, a fishing trawler finds the decomposing body of Billy Miles (Zachary Ansley)—an alien abductee who was taken at the same time as Mulder.

When Miles revives on the autopsy table, Skinner, despite Doggett's objections, orders that Mulder's body be exhumed and brought to a hospital, fearing that he may have been buried alive.

From her medical findings, Scully discovers that an alien virus is keeping the abductees alive long enough to cause a radical genetic transformation to take place, similar to the one that Miles experienced.

Skinner explains Krycek's demands, but Doggett argues that both options are unreasonable because either Scully's child will die, or Mulder will succumb to the virus.

[8] Desiring closure if the show was cancelled, X-Files creator Chris Carter brought back several characters from the series' pilot for the season finale "Requiem"; this included most notably Billy Miles, played by Zachary Ansley.

After an eighth season of the show was confirmed, the mythology of the ongoing alien story arc for the series changed for both practical and artistic reasons.

[10] To replace him, the show's producers hired Robert Patrick, although Duchovny eventually agreed to return for half of season eight's episodes.

[11] Further, Frank Spotnitz, executive producer and co-writer of "Deadalive", noted that the original mythology of the show had been "wrapped up" much earlier in "One Son" and "Closure".

[12] To create a "new chapter" in the mythology, and to work around Duchovny's absence, the storyline for the eighth season focused largely on the search for Mulder in the first half and the introduction of Super Soldiers in the second.

"[15] The funeral was expensive to film; several actors, such as Sheila Larken, who played Scully's mother, needed to be flown in specifically for the scene.

"[16] Despite the fact that the show was filmed in California and under "huge financial pressure", real snow was used for foreground shots[17] and the background was painted white in post-production.

[19][20] On Duchovny's request, Spotnitz and Carter wrote a larger role for Skinner than usual,[21] giving him the "moral dilemma" of whether or not to kill Scully's unborn child or Mulder.

[22] In the end, Spotnitz called the effects of his actions, particularly the aftermath of taking Mulder off life support, a "nice sort of unexpected turn".

[23] Scully's role in "Deadalive" was partly based on the 1954 film Magnificent Obsession, in which a young man's behavior causes him to accidentally blind a woman.

[26] Spotnitz managed to secure sufficient funds to enable the fishing trawler scene to be filmed off the Los Angeles coast, a situation with which he was "very pleased".

Spotnitz commented on the irony of "paying all this money to get [Duchovny's] services for a limited time" only to have him spend most of the episode "in a hospital bed, semi-dead".

The arc would continue in "The Gift", which explored the implications of Mulder's inoperable brain tumor and featured the resurrection of a temporarily deceased John Doggett.

[39] According to scripture, Jesus spoke these words when he raised Lazarus of Bethany from the dead, and many biblical scholars note that the verse foreshadows his own resurrection.

In the Gospels, Jesus is brought back to life but then leaves his followers, allowing them to spread his message; this is recorded in Acts, the fifth book of the New Testament.

Robert Shearman, in his book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, gave "Deadalive" a full five stars, applauding the episode for being a "slice of sci-fi hokum, with action scenes, bits of grisly horror [and] a reexamination of the show's mythology".

"[7] Likewise George Avalos and Michael Liedtke of the Contra Costa Times praised the on-screen return of characters such as Mulder and Krycek.

They felt so many eighth-season episodes worked well because "Chris Carter seems to be taking an even more active role in the series that is most closely identified with him.

Handlen also positively commented on both Anderson's performance—although pointing out that she "is largely pushed to the side for the majority" of the episode—and Lea's reappearance, noting that "it's always fun to see Krycek".

[51] SFX magazine ranked the episode as the sixth "Top 10 Resurrections", reasoning that it allowed Mulder to be around for what was then the series finale a year later.

However, the magazine felt his return made "poor Robert Patrick’s Agent Doggett a bit superfluous", and that the plot was rather complicated.