The term "Faction Calculus" is the phenomenon when a faction takes on a specific role in light of other factions. Differences are heightened when contrasted to each other.
Faction Calculus entry in TV Tropes
To summarize, when there are:
Two factions: Usually splits between a powerhouse faction and a subversive faction.
Three factions: A balanced faction joins the powerhouse and subversive.
Four factions: The balanced splits into balanced and glass cannon factions.
Five factions: A horde factions splits from the subversive faction.
Six or more factions: Faction calculus fails and factions are categorized by another system entirely.
Factions are probably my favorite "feature" of real-time strategy games, and hence why this blog is named after it.
I liked Calculus when I took it in school, but I'm probably not the best at it. That said, I love to analyze.
With this blog, I aim to cover as many real-time strategy games as I can and play them.