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 ARC 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 Doom Slayer arrives at the top of the ARC Complex, the ARC Intern is the first one to greet him, guiding him to the Demonic Crucible, and informing the Slayer that Samuel Hayden was convinced he'd 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 Hayden'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 ARC 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.

After the Slayer resurrects the Seraphim and returns to the Carrier, the Intern interrupts his supervisor to explain to the Doom 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.

Once the Doom Slayer returns from the Swamp with the Dark Lord's Life Sphere, all other ARC Employees evacuate whilst the Intern remains, as he wants to be a part of the Slayer's plan. He informs the Slayer that he'll be able to enter Urdak as long as he has a Life Sphere, of which he is currently in possession of the Dark Lord's. The Intern prepares the portal and bids farewell to the Doom Slayer, referring to him as "Doomguy" before apologizing under his breath.

The Ancient Gods, Part Two
The Intern returns in the second expansion, 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.