Intern

The Intern (sometimes referred to as ARC Scientist) is an unnamed employee working at the ARC Complex, and a supporting character in Doom Eternal and The Ancient Gods DLC. He is often depicted as one of the only few humans in the game that doesn't fear the Doom Slayer, as he appears as a fan of the protagonist.

Doom Eternal
Prior to the first Marauder encounter in Mission 6, the Doom Slayer enters the ARC Complex looking for the Crucible, where he encounters The Intern, who eagerly walks up to him and informing him that Samuel Hayden knew he would come eventually for the weapon. After the Slayer gained the Crucible, the Intern explains to him how it is an honor for him to meet him, before ultimately getting bumped out of the way by the Slayer. Shortly after, when the Slayer finds the remains of Hayden, the Intern explains how the ARC couldn't revive Hayden as they could not gain access to his main cortex due to it being alien. He then explains how they were preparing for Hayden's careful extraction with specific orders before the Slayer ripped Hayden's remains right out of the structure.

The Ancient Gods: Part 1
The Intern appears again to aid the Doom Slayer, as the ARC assist the Slayer and Hayden in finding the  Seraphim. Operating from the Mobile Command Carrier, the Intern activates the portal to send the Slayer to the UAC Atlantica Facility.

When the Slayer returns from the facility, the Intern interrupted the ARC Supervisor from speaking to the Slayer, as he explains to him that Samuel Hayden is the Seraphim and expressing his surprise that the being had been working with them all along. From this point onward, with Hayden/Seraphim incapacitated, the Intern acts as the Slayer's guide, speaking about his objectives throughout the Blood Swamps and the Holt.

After the Slayer destroyed The Father's Life Sphere and taking only the Dark Lord's essence, when all the ARC staff was evacuating in terror of the Dark Lord's essence the Intern is the only ARC personnel who was brave enough to remain and help the Slayer in his plan to revive the Dark Lord and then killing him further to destroy all the demons.