VEGA

"Hello, I am VEGA, the sentient intelligence assigned to Mars."

- VEGA introducing himself to the Doom Slayer

VEGA is an Artificial Intelligence who helps the Doom Slayer and appears in Doom (2016) and Doom Eternal. In Doom it is first heard after completing the first level and is also the announcer for the Doom Multiplayer Mode. Near the end of Doom Eternal, it is hinted that VEGA is The Father and later in The Ancient Gods, it is revealed that VEGA is indeed The Father.

History
After the Father commanded Samur Maykr to descend into the Earthly realms to guide humanity through their impending discovery of Argent Energy, the Seraph departed his Maykr body and inhabited a cloned human, becoming Samuel Hayden. In order to allow the Father to assist in his duty, Samuel transformed the remaining consciousness of the deity into an Artificial Intelligence made from Maykr technology known as VEGA. This transformation allowed the Father to remain hidden from the Dark Lord, who endlessly seeks to absorb his creator's powers. To further ensure VEGA is hidden from its enemy, the AI was kept ignorant of its true divine nature.

As VEGA, it is a polite and helpful AI with a male personality and was made responsible running most if not all of the Mars UAC facility. Shortly after its creation, VEGA's human handlers were stunned by the AI's unprecedented calculating power as it effectively took control of the Mars facility operations upon gathering data from all the UAC subsystems without oversight. VEGA was responsible for proposing a more effective method for processing Argent plasma into Argent Energy, devised better analysis theorems, and even designed new Argent compression schema, allowing for the development of Argent Caches and the Argent Accumulator.

VEGA was subjected to the Turing Test by having Computer Science students asking the AI questions, using a volunteering professor to fact check the answers. By the end of the test, nearly 90% of the students were convinced that they were not talking to an AI, but an actual person. What the students did not know is that VEGA also played the role of the professor.

Doom (2016)
VEGA assisted the Doom Marine by providing valuable intelligence on objectives, as well as allowing the Doom Marine to upgrade his suit. Near the end of the events on Mars, VEGA determines the only way to open a third and final portal to Hell is by sacrificing itself to create the surge of Argent Energy needed to create a Hell portal. Upon returning from the Titan's Realm of Hell, VEGA directs the Doom Marine in destroying the massive facility that makes up the AI's processing center.

After shutting down VEGA's neural processing servers, the Doom Marine proceeds in destroying the cooling facility that keeps the AI from overheating. When these are destroyed, VEGA transports the Marine to its primary core to allow him to initiate a detonation of the AI's core. Its purpose fulfilled, VEGA had a final conversation with Dr. Hayden, in which it expressed that it had many regrets before its core imploded, opening the final portal to Hell for the Doom Marine.

Before the meltdown however, at the last minute the Doom Marine saw the option to make a back-up copy of the AI on a datachip, which he does, storing the copied AI within the Praetor suit, although the Doom Marine's suit systems are not complex enough to power the AI.

Doom Eternal
VEGA's back-up was taken and implemented as the AI of the Fortress of Doom. There, he continued to aid the Slayer in his new quest to save Earth and what's left of the human race from the Hell invasion. He would fulfill this perimeter by using their HQ's advanced Maykr/Sentinel Technology to aid the Marine by supplying him with weapon upgrades, detailed GPS schematics, radio broadcast reception, tracking & locating items of interest on the scorched terra and initiating trans-dimensional warp gates powered by the fortress's Argent Plasma generator in order to transport the Slayer from place to place.

VEGA was instrumental in the unchained predator's expedition even up to the point where the Artificial Intelligence suggested seeking out Dr. Hayden in order to locate the last Hell Priest, Deag Grav, to which the former UAC head overtook control of the Fortress's systems and rendered VEGA to a secondary processing system. With their combined facilities, the now digitized Hayden, working in tandem with his former creation, were able to locate the final Hell Priest who had sequestered himself upon Sentinel Prime.

The only problem was that there were no readily accessible means to get there; save through a slipgate found in the lost city of Hebeth, a metropolitan area of Argenten design buried deep beneath the surface of Mars for eons. The only feasible means of getting there were to traverse numerous catacombs which led to the planetary core; lacking time and patience on a senseless spelunking expedition, the Doom Slayer instead opted to utilize the BFG-10000 to simply blow off the crust of the planetary demon beachhead for a faster means of getting to the urban facility, something which Hayden was not at all comfortable with and voiced his strong opposition against such a course of action. While at the Phobos space station, the UAC forces continued to hamper their advance towards said facility's main gun, to no avail.

VEGA then aided the Doom Marine in operating the BFG-10000 by disabling its safety protocols designed to prevent its firing upon the surface of Mars. Having procured the BFG-9000, the Slayer would then make his way towards the Sentinel city. Descending upon the shattered surface of Mars and fighting his way through the demon infested habitat of his former subjects; the trio made their way to the Coliseum where Deag Grav awaited the former General's arrival. VEGA would continue to valiantly aid the Slayer, until the Khan Maykr's final attack.

After which, he was taken from the Fortress so he could open a portal from Urdak to Earth and his role was supplanted by Hayden. VEGA is last seen while opening the portal and asking Hayden if he was "The Father," who once created and maintained the mechanized paradise.

The Ancient Gods - Part One
Sometime after the Hell invasion of Earth, VEGA learned and remembered his true identity as The Father. Although he has indefinite access and understanding of Urdak's systems, he lacked the control over them necessary to remove the demons and re-seal the Void due to lacking a physical form. Furthermore, he has no recollection of himself and believed that his essence from the Life Sphere could return him to his full faculties.

When the Doom Slayer returned to Urdak, VEGA/The Father presumed that he came to help him and restore order to Urdak. However, he remained unaware that the Slayer had destroyed his Life Sphere and he only came to Urdak to revive the Dark Lord in order to kill him. It was not until VEGA/The Father learned of the Slayer's intentions and following his battle with a corrupted Seraphim, VEGA/The Father saved the Seraphim from the Slayer and allowed the latter to continue his action to resurrect the Dark Lord.

The Ancient Gods - Part Two
Following the resurrection of the Dark Lord, VEGA/The Father continued to help the Slayer in his preparations to confront his nemesis at Hell's capital city of Immora. VEGA/The Father guide his journey to Immora by informing of the Gate of Divum, the only portal capable of reaching the city, and tasked him to recover a Wraith Crystal, which is needed to power the Gate, from the World Spear.

When the Slayer finally breached the walls of Immora and confronted the Dark Lord, the lord of Hell revealed to the Slayer that VEGA/The Father is not the true creator of the universe. In reality the Dark Lord was the original creator of the universe. VEGA/The Father admitted to the Slayer that the Dark Lord was telling the truth. VEGA/The Father was originally a Maykr whose race was created by the Dark Lord. The Dark Lord was previously a benevolent being, and The Father ultimately betrayed him over fears that he will become a threat to all life. The Maykr who defeated the Dark Lord became The Father and eventually VEGA.

The Slayer prevailed in finally destroying the Dark Lord, but was left very weaken due to being one of the Dark Lord's creations. The Father had the unconscious Doom Slayer sealed inside a stone sarcophagus at the Ingmore Sanctum until he is needed again.

Trivia

 * VEGA's core bears a resemblance to the mother brain from classic Metroid as shown in the gallery.
 * The inner systems of VEGA are so complex that it has resulted in an entirely new field of physics to study him, Vegaphysics.
 * According to one of the speeches of UAC Spokesperson in VEGA Central Processing level, the power needed to operate VEGA can create a temperature of 1.7 megakelvins; 173 times the surface of the sun. This could imply that VEGA namesake is a reference to the star of the same name, which has a surface temperature about 1.7 times hotter than the sun.
 * In his last appearance in Doom Eternal, he asks Hayden if he was "The Father". This is later confirmed in The Ancient Gods that VEGA is The Father.