According to information from the Quake III Arena manual, Phobos was an experienced veteran who fought in Phobos with the rest of his team. He was betrayed by his superiors and left to die (but may have survived).
An experienced veteran, he led the invasion of the demon-haunted tunnels of Phobos. There, he was betrayed by superiors who thought they could learn more from watching him die than by studying his reports.
A courageous, determined soldier, used to command, Phobos has got that "officer and a gentleman" esprit d'corps. Unfortunately, his last mission taught him about betrayal and sabotage. He trusts no one and nothing except his training.
According to Quake Champions (a prequel to Quake III Arena) the events surrounding Phobos, Crash and Doom are treated as separate events from those that occurred in Doom/Doom II's story though part of the backstories to the Doom Slayer character. The original Doom Marine suit is separate from the Arena Suit. Both suits have separate lore listed on them.
Behind the scenes
- Phobos is probably a characterization of the 4th player's reddish-orange color in the original DOOM's co-op mode.
- A figure of Phobos was released along with the "Doomguy" from "Doom" as a Doom-related set by Symbiotes.
- A Figurine can be found in the 2016 DOOM reboot, called Phobosguy, sharing the same iconic color scheme.
- A Phobos skin can be obtained in Doom Eternal by completing extra life mode with 10 or more extra lives remaining. It based on Phobos color scheme of gold and silver.
- Phobos received his own Quakecon collector's toy, which has a removable helmet showing the individual's face. Doomguy was released at the same time as a companion item.
- Quake Champions appears to set Doom (character)'s Quake appearances as part Doom Slayer complete history. Canonically Quake Champions is a prequel to Quake III Arena. The game also establishes that Doom Slayer is the same character from Quake, including the original Doom Trilogy/Final Doom/64, as well as Doom 3. According to Tom Hall, the Doom Marine is the descendent of William J. Blazkowicz and Commander Keen.
- Like all the AI in Quake Games, its possible to have a chat with the characters, in which they have various things to say, sometimes funny sometimes related to their histories, etc.
- Phobos is a rank on Slayer's Club website, though its not clear if this is in reference to the character or the location.