So, this morning, I found this. It is a fair point that must be made about Megadungeon design, and philosophy. And this is not something I have used too much thus far. Back in the early days of the development of the campaign, Ludos <wants to eat> Goblins <wants to sack> City <wants real estate back> was about as far as it went. The 'Old City' level had goblins, and rats, and well, that's about it. Nothing that really had a structure of co-operation or of antipathy towards one another. The early stuff is eat or get eaten, about as simple as it gets for interaction between groups.
Since then, there has been a coven of hags added to the 'Old City.' In the playtest, the party destroyed this coven (and the goblins for that matter). As they didn't co-exist in real time, I hadn't thought about how they would exist in game-time either. I will rectify that right now:
The 'Old City' houses a few different groups that have eked out power bases. From weakest to strongest these are:
Black Ants on the verge of extinction from Red Ants
Dire Apes able to secure a single home inside the 'Old City' Their number is small (5) but they are more physically dominant than most of the surrounding factions.
Goblins (in the Old Citadel) winning the numbers game at the beginning of the campaign
Orcs (Black Heart Tribe) badly equipped and unable to hold territories for long.
Orcs (Black Eye Tribe) split from the Black Heart Tribe, due to 'weak leadership' Took the strongest warriors with them.
Gnolls (unknown name Tribe) able to hold territory due to shrewd negotiations with neighbors.
Red Ants aggressive and nearly destroying primary competitors, the Black Ants
Baen's Circle are 9 Hags bent on bringing the Glabreazou back to (life? this plane?)
Gnolls (Smash Tooth Tribe) another Gnoll tribe who holds territory due to cunning deals. Also have ogres, orcs, and a troll in their tribe.
There may be more on that first level, but those are the ones that the party has heard of. Here are some interactions between the groups:
Black Ants only interact with Red Ants, and are losing their war for survival.
Dire Apes keep to themselves, and are satisfied with the basic necessities.
Goblins attack all who enter their home (the Old Citadel). They are generally killed when stepping foot outside of their small area.
Black Heart Tribe attack goblins on sight. They avoid Black Eyes as much as possible.
Black Eye Tribe attack Black Heart Tribe on sight. They blame the 'Hearts' for the Orcs not being the most dominant group in the city.
Gnolls (unknown tribe) negotiate with anyone who they can. They trade information for necessities.
Red Ants avoid most other social groups. They are attempting to become the primary carrion eaters in the area.
Baen's Circle will charm any humanoids they come across, and use them until they are dead. Otherwise they avoid contact to remain unnoticed in the Old City.
Smash Tooth Gnolls have been feeding the Red Ants carrion, and generally interact with everyone else as Neutral reactions.
There you go, a short list of how the groups interact with each other in the Old City. There are individuals too, that can change these balances (hydra, dragons, etc.) Those are singletons though, and are easily able to overpower all except the Hags.