"G-man is absolutely more than merely what he appears to be. But what exactly that is can never be answered with confidence."
:)
May I indoctrinate you into my theory?
I think the G-Man's employers are the upper echelon of the Combine. His purpose is to monitor mankind's progress on interdimensional teleportation technology and report back to them. The Citadel explosion is a flare he managed to send to the Nexus via Gordon, signaling that Earth was closing in on the Combine's goal.
His actions often serve to break up and displace human command structures - both Combine and Resistance - but rarely, if ever, strike at the Combine's head enchiladas themselves.
Moreover, in this theory, he got put in the Vault in HLA after his bosses caught wind of his unauthorized extraction of Alyx from Black Mesa. Alyx's rescue of him serves as the ultimate proof of his investment and an "I told you so" to his employers.
The legs of the argument are:
1.) Conservation of narrative detail. While it's possible the G-Man might come from an alien species we've never seen before, it wouldn't make sense to introduce new players this far along in the narrative. The only party we've never been officially introduced to who would fit his employers' criteria are the Combine themselves.
We know the G-Man isn't a Nihilanth because the Singing Vortigaunt's words suggest that Gordon had killed the last Nihilanth. We also know the G-Man isn't human, thus nixing notions of him being a time-traveling Gordon, because the Nihilanth says, "You are man. He is not man."
If we eliminate "he represents the developers" as a non-diegetic answer, that leaves us with three diegetic possibilities: Combine, Vortigaunt, or unseen third party. The last is one big question mark, and since we don't have enough evidence to confirm or rule out a Vortigaunt identity, Occam's Razor would suggest Combine.
2.) At the end of Half-Life, the G-Man tells Gordon "The borderworld, Xen, is in our control for the time being, thanks to you."
Now think about what happens directly after. The Combine invade Earth.
It logically follows that the "us" who control Xen must be the Combine. They know they need the borderworld as a strategic chokepoint because it is the "dimensional slingshot" used for teleportation, so they're not going to give it up. Gordon may have simply cleared the way for them by killing the Nihilanth.
It would also explain why the Combine are so desperate to find a way to master local teleportation technology, as they can use Xen as a one-way ticket to get to Earth but become stranded once they arrive here. Judith also says that they've failed to factor in the "dark energy equations." They're basically using the Resistance to finish their homework.
3.) In Half-Life: Alyx, the G-Man tells Alyx that removing the Combine from Earth would be "too large [a nudge], given the interests of [his] employers." Who benefits from keeping the Combine on Earth, if not the Combine?
Okay, you might be asking. Why does the G-Man guide Gordon to the Citadel's destruction? Doesn't that go against the Combine's interests?
Only the human side. Breen loses his power, if not his life (if you believe he didn't turn into an Advisor grub in Episode Two), and Overwatch gets sent for a loop, but does it really result in the Combine head honchos taking a hit? The Resistance seems to think so, but I'm not so sure.
During the final boss fight against Breen, you can see the portal open to the sight of the Combine Nexus. Breen intends to teleport there and obtain a suitable host body, which the Advisor had suggested he use in order to survive the environment.
Perhaps the G-Man needed Gordon to kill two birds with one stone: kill Breen to sever human control of the transhuman branch of the Combine, and send a ping to the Nexus via the Citadel explosion to signal that Earth had found some important teleportation tech, or perhaps had perfected the tech (Kleiner's "very slow" teleport).
Also, who says he's working against company interests? Who says he's not cooking the books?
I don't think the Combine "captured" him and put him in the Vault in the sense that they so happened to trap him like a stray cat, because honestly, he seemed way too calm and expectant.
I think he maliciously complied with some sort of disciplinary action so that he'd be able to rub it in their faces later after Alyx, against all odds, infiltrated the Vault's security and freed him. After all, he tells Gordon in Episode Two that he had to learn to ignore the haters when they insisted that she was a "mere child of no practical use to anyone." Now it's kind of like he's getting the last laugh.
Another question someone might ask is, "If the G-Man is part of the Combine, how can the Vortigaunts suppress him?", which is a bit misleading because it assumes the Combine are infallible gods.
The Combine clearly know Vortigaunts present a threat because they use them as batteries to power the Vault and keep the G-Man at bay. They siphon their energy, suppress them via subjugation and violent torture, in part BECAUSE the Vorts are too powerful otherwise. They don't want humans and Vorts teaming up because they need the former to finish their homework and the latter to keep the lights on, essentially.
Now, take this thought and consider it within the context of why the G-Man might try to plant seeds of doubt in Gordon's head about the Vortigaunts' alliance in Episode Two. Why he mockingly calls them his friends. "There was a time when they cared nothing for Miss Vance. When their only experience of humanity was a crowbar coming at them down a steel corridor." Why he looks so pissed when he tells the Vortigaunts who rescue Gordon and Alyx from the Citadel explosion: "We'll see… about that."
Alyx notes one flaw of the Combine: they can be "slow to wake." The only advantages the Resistance have are stealth (which is really just borrowed time) and the time it takes to hurl a rock between the giant's eyes before it can land a blow. Meaning even if the G-Man had pinged them through the Citadel explosion, it would probably take the upper echelon time to assemble a response: time that the Resistance could use to destroy the Borealis.
Yeah I read your theory about G-man being Combine before and had it in mind when writing that post lol.
I think it makes sense, and fits well with what Marc wrote about in his personal episode 3 fanfiction lol. I REALLY like the idea of the Combine having a Dyson Sphere, that would be just the perfect revelation to really drive home how impossibly big and powerful they are, that all humanity has done since Half Life 2 is the equivalent of ants biting the bottom of a shoe sole.
The concept of G-man basically just doing the fourth dimensional intergalactic equivalent of passive aggressive office politics would fit very well into that idea. That he's using humanity as a convenient pawn in their own little game of thrones. Either on his own interest or in the interest of superior authority that he answers to within the top brass of the Combine.
Probably a low brow comparison, but if you've seen Robocop you could liken it to the boardroom backstabbing by the OCP characters. Robocop was only created as an underhanded corporate scheme to try gun for a promotion at the expense of a senior executive. Something like that could be what's going on with G-man and whoever he may or may not answer to.
That idea would also support the cosmic horror themes of the series. Xen and Nihilanth are very classic eldrich concepts, but the idea of the Combine not as a generic evil alien overlord force but as a white collar organization represented by a literal man in a two piece suit and tie? That the survival and struggle of humanity against their omnipowerful oppressors is nothing more than the result of convenient boardroom politics? That the only possible hope we have as a species is not really being worth the effort to wipe out completely after we sever the link between Earth and the Combine giant proper? That's almost more of a white collar cosmic horror, which would tie everything back to the office space environments of Black Mesa.
It's definitely an imagination stoking possibility. I don't know if we'll ever truly see the full picture come together though. And I have zero faith that Valve had any of that in mind when just developing the original Half Life lol. As far as the original Half Life goes, G-man is absolutely a question without even the possibility of an answer.