Picture, if you will, a small village. Just like any other village there are streets and alleyways, shops and homes, open spaces and meeting places. People live here from all walks of life – the poor & lowly and the rich & powerful alike. There are the butchers, farmers, priests and leaders all tossed into the melting pot of village life.
Now put a lid on it and site it underground.
Next time you’re designing a dungeon think of it like any other town or village. The dungeon corridors are your streets with each room a home or communal space shared by the residents. When your players ask why a group of Orcs is in a room next to an Ankheg’s lair, just explain “because they’re neighbours”. We don’t question why a vicar might live next to a car salesman, and the same applies here.
Thinking of a dungeon as a small community has a major impact when it comes to designing the layout. Rooms are less likely to be used as thoroughfares with exits on all walls but instead have a front door and (possibly secret) back door. Larger rooms will either be occupied by the more powerful and influential monsters or be shared spaces where dungeon occupants will come together.
Your Dungeon Town will need much the same amenities as any small community – waste disposal, food, education and trade. The limited resources of the Underdark mean than even the lowliest Kobold will have better green credentials than your average surface dweller. Any waste produced will most likely become compost to aid the mushroom harvest. Either that or it explains why there are so many covered holes in the ground – that’s no pit trap; it’s a toilet!
A Goblin Cult Lair, for example, would most likely consist of many small living-caves with the three larger caves serving as nursery, worship area and Goblin Boss’s Cave. The sound of battle in the worship area or nursery will almost certainly bring Goblins from the surrounding area into the fray (add 1d4 more Goblins each round) whereas the noise of battle in the Goblin Boss’s Cave won’t. He might just be having a Bad Day, and it’s best to avoid those.
Beyond their usefulness when defending their lair, each monster will serve a role in the community. That role might be nothing more than “Bert’s friend” or “Dungeon Idiot”, or it could be something vital. That Goblin Cutter could be the resident cobbler (hence his lack of skill in combat) or a mushroom harvester while the Ghoul in the next room be the Dungeon’s medic. If nothing else, giving the monsters roles raises them beyond just being “4 Goblin Cutters” in an encounter and gives you something more to work with at the table. The other monsters could fly into a frenzy when your heroes kill the Orc Guard who happens to be the only eligible female in the Dungeon, or give a snicker when the local bully finally gets his comeuppance.
Food for thought, anyhow.