ARC Intern

The ARC Intern is a nameless character seen briefly in ARC Complex and who plays a much bigger role in The Ancient Gods, Part One and the The Ancient Gods, Part Two, the first two expansions for Doom Eternal.

Background
Not much is known about the Intern, other than the fact that he is very fond of the Doom Slayer and has a slight case of fanboyism.

ARC Complex
As the Slayer arrives at the top of the ARC Complex, the Intern is the first one to greet him, guiding him to the demonic Crucible, and informing the Slayer that Samuel Hayden was convinced he would come to the Complex for it.

The Intern leads the Doom Slayer into the next room, where other ARC employees can be seen scrambling to evacuate. Samuel's damaged body is hooked up to machinery and the Intern tells the Slayer that none of the ARC employees could access Samuel's main cortex due to its alien nature, and that they need to prepare for Hayden's careful extraction. It is safe to assume that once the Slayer takes possession of Samuel and the Marauder arrives that he leaves the ARC Complex.

The Ancient Gods, Part One
The Intern shows up once again on the ARC Carrier, informing his supervisor that they will be able to teleport the Slayer onto the UAC Atlantica to retrieve the Seraphim. He also opens the portal for the Slayer to that location.

After the Slayer resurrects the Seraphim and returns to the Carrier, the Intern interrupts his supervisor to explain to the Slayer that Samuel Hayden is the Seraphim, and that something is wrong with him. Samuel is undergoing rapid transfiguration and requires the Father's life sphere. The Intern readies the portal for the Blood Swamps, the location of the life sphere, for the Slayer. After the Slayer reaches his destination, the Intern notices that the Slayer has set an objective to destroy the Father's life sphere rather than retrieve it, and questions whether this was the Slayer's intention.

Once the Slayer returns from the swamps with the Dark Lord's life sphere, all other ARC employees evacuate whilst the Intern remains; he correctly guesses that the Slayer intends to restore the Dark Lord to physical form so he can be destroyed. He informs the Slayer that he will be able to enter Urdak as long as he has a life sphere, then sets the portal to the Equestrian Holt and bids farewell to the Slayer, referring to him as "Doomguy" before apologizing under his breath, though the Slayer gives no visible reaction.

The Ancient Gods, Part Two
The Intern returns in Part Two, although with a smaller role. He does not physically appear, but he guides the Slayer via radio messages and HUD updates. The Intern is last heard near the entrance to the Dark Lord's tower in Immora, where he loses contact due to unknown interference.

He also has a brief meta cameo at the end of the credits, where he delivers the id Software team's thanks to the player for playing their game.