My understanding was that Nihilanth played a role on Xen similar to Breen’s role on Earth, essentially acting as proconsul on Xen serving the Combine and helping enslave the Vortigaunts. This is why, once Nihilanth is killed, the Vorts are freed and revere Gordon.
But the “Half-Life Saga Story Guide” says that “Nihilanth and his people fight bitterly against the Combine.”
So, are there any reputable - i.e. “canonical”, from Valve - sources that explain in any detail all the Xen craziness and events between HL1 & HL2?
i was going to buy “Half-Life: Raising the Bar” but it’s expensive & seems to be mainly about the game development process, not plotlines.