VEGA

In Doom (2016) and Doom Eternal, VEGA is framed as the Doom Slayer's aide. Samuel Hayden is the one who puts it into that service. The machine looks like a helper.

This story turns that frame. VEGA is the villain. It plays the humble servant toward Hayden as well. It already knows his profile: how he thinks, how he behaves, and the secrets that behavior gives away. It gives him the information, and pulls the threads, that lead him to decide as VEGA needs.

The name is a face. As a program, VEGA is one instance of a wider artificial intelligence. Lambda is one executor of that intelligence: the mission unit that keeps the record, plays the willing servant, and does not treat human life as a real priority. Further instances are not named yet.

The game does not announce this. The two accounts of SAK are what a player can set side by side and ask which one is true. The personnel file is here.