We have maps for the world, maps for a few sample settlements, ideas for mapping the dark parts of the hive. We have races and cultures spread across the world, and a few mysterious entities hidden in the shadows. Among the cultures we have castes of occupational types, but we haven't really detailed the specific jobs that characters might do. Similarly, we haven't developed the ways different groups interact with one another.
I like odd numbers when it comes to interactions between factions. Standard politics with left-wing and right-wing ends up pretty static. Balanced groups of light and darkness, law and chaos, good and evil. They're just too simplistic for me, they don't offer a dynamic tension capable of twisting and turning as events shift...they just go back and forward on the same track. Trinities offer a range of direction when tensions are applied, five way oppositions (like those found in Chinese alchemy, or Magic: the Gathering) offer this kind of tension as well.
I'm thinking of 9 general factions in addition to some factionless outsiders. Three groups of three.
For each faction within the three groups, there is a common theme. Then each group has a faction that wants to eliminate the theme, one that wants stability within the theme, and one wanting enhanced strength for it.
The factions group themes are: Civilisation, Shellbrood, and Hiveguard.
So that gives us...
1. Eliminate Civilisation. Bandits.
2. Stabilise Civilization. Merchant Guild.
3. Strengthen Civilisation. Imperium Military.
4. Eliminate Shellbrood. Brood Hunters (masters of killing the Shellbrood)
5. Stabilise Shellbrood. Brood Wardens (defend against the Shellbrood and keep them away)
6. Strength Shellbrood. Brood Riders (believe they can control the Shellbrood and harness them)
7. Eliminate Hiveguard. Hive Liberators
8. Stabilise Hiveguard. Hive Scholars
9. Strengthen Hiveguard. Hive Masons
...no, actually, I don't like that. It works at some level, but it feels a bit contrived.
How about a 5-fold tension, based around different methods that people might use to gain power within the setting?
1. Social Power (using people to get achieve your goals)
2. Fungal Power (using the various growing entities to achieve your goals)
3. Scholarly Power (using knowledge and the applications of that knowledge to achieve your goals)
4. Mystic Power (using psychic potential and rituals to achieve your goals)
5. Direct Power (using physical force and aggression to achieve your goals)
Do any of these seem to be natural opponents to one another? Do any of them seem to be natural allies? That's something which will help define the setting in a subtle way.
Let's say fungal power is generally "anti-social", because it focuses on the funagl growths ahead of the people in the setting. Scholarly power seems to oppose direct power, where the former monitors how things work before it applies a force, the latter just applies the force then hopes the ramifications are positive.
Mystic power could easily be an ally to them all. It's even tempting to throw an elemental spin on the various powers due to the correspondences that have been chosen... In tirn, this links back to the work I've already done on System 4, so it's either a nice coincidental synergy, or just something that sits it the back of my mind constantly, informing various design decisions.
Social = Air
Fungal = Earth
Scholarly (Mental?) = Water
Physical = Fire
Mystical = Void?
But I don't like my factions being too single minded. How about we link "non-opposed" elemental methodologies in pairs... Each faction has two elemental ways it tends to gain mundane power, or a single element with a mystical pairing...
Air-Water: focus on traditional mundane politics, diplomacy and trade.
Air-Fire: focus on rallying groups of people to wage war and conflict.
Earth-Water: focus on improving the people and their wellbeing through farming and growth.
Earth-Fire: focus on defending their community through strategic use of fungus and firepower.
Air-Void: focus on mystical methods to control people.
Earth-Void: focus on attaining the most power from fungal symbiotes.
Fire-Void: focus on developing martial prowess to superhuman levels through magic
Water-Void: focus on the arcane relics of the past and mastering their powers.
Any factions sharing an element with one another might see potential allies, and any factions without elements in common at all might see potential threats (or just don't understand each other). Each of the factions using "Void" as a paired element would be considered uncommon, while those without void would be considered common factions.
Maybe a settlement of people will have influence in it from a number of factions based on it's population. Only the smallest barricade slums would be under the control of a single faction, most small settlements would have a pair of factions at work in their population, larger settlements might have three or four, and the largest villages and towns might have five or six. Only the biggest two or three towns might have representatives of every group regularly frequenting them (or in positions of power).
This definitely starts giving us a good structure to hang occupations onto, it adds a level of subtlety to the conflict under the obvious fights between the two major "civilisations" in the setting, and the possible racial/cultural tensions. More ways to bring about tension are mare ways to bring about story.