How well do the monsters and NPCs of your dungeon get along with each other? Here is a pair of tables for use when randomly (or semi-randomly) stocking dungeons to establish the relationship of dungeon neighbors or at least spark a DM's imagination.
Check room/chamber or set of rooms/chambers as appropriate to the dungeon.
What do the monsters even know about each other?
3... Rumors, only has a bare notion of neighbors presence and activities based on what others have said.
4... Aware, knows a bit about neighbor but likely lacks some significant details
5+.. Contact, informed and moderately knowledgeable about neighbor
Roll 1d6 for a wild an unorganized section of dungeon. roll 2d6 for an organized section of dungeon.
If monsters are aware or in contact with each other check for their relation, either roll once for a relationship or roll for each side of relationship, if players discover the goblins in room 47 actually dislike the Hobgoblins in room 49 they may be able to exploit that.
Dungeon Neighbor Relations
-2…. Openly Hostile, will exploit situation to own advantage
3-4… Antipathy, likely to ignore combat small chance to join interlopers
5-6… Dislike, may assist in combat of town advantage, may harbor refugees briefly
7….. Neutral, may assist in combat of town advantage,may harbor refugees briefly
8-9… Tolerant, possibly help in combat, may harbor refugees briefly
10-11… Cooperative, likely to help in combat, will harbor refugees
12+….. Allied, will run to help in combat unless clearly beyond their capacity but will still aid allies.
roll 2d6 normally, 3d6 in a dungeon,level or zone dominated by a faction.
apply modifiers if desired for alignment differences or obvious power dynamic issues. No more then -2 or +2 for each such issue is recommended.