Fundamentally, I'd like to argue that monsters are fundamentally territorial, but that this does not necessarily mean that all monsters are necessarily locked to a given place. Some monsters wander; some do not. Some monsters form structure; most do not. The framework I propose is meant to devise a monster for a space that will do more than occupy the space, it will define the space, helping to fill the emptiness of wilderness hex crawls.
For this, I'd rather not discuss monsters individually, so I'll propose five general monster "types." I don't mean this list to be necessarily inclusive ~ there are bound to be monsters that don't fit these types ~ but I think these would include at least 95% of the monsters with which we're familiar. The six groups are vermin, passive wanderers, destructive wanderers, builders and eradicators. I'll set about giving a definition for each:
- Vermin are monsters that can live anywhere without especially affecting their environment. They can live within urban areas and subterranean complexes, they can occupy lands that are essentially unproductive, they can live in rich lands occupied by other creatures. They are effectively pests to every other monster, regardless of the monster's intelligence or agenda. The more obvious forms are various bugs, worms, rodents and other small beasts, mostly acting as scavengers or parasites. This might include magical creatures that survive as thieves or deliberate annoyances.
- Passive Wanderers include a great many herding animals and beasts of enormous size, mostly herbivorous or otherwise non-destructive, potentially occupying great areas of land by sheer numbers. It would also include beasts preying upon the herds. On the whole, passive wanderers would occupy land of minimal commercial value, establishing such regions as "territory" because of the eradication of plant material as the herd moves in and eats everything before departing. Since permanent occupation of said lands by intelligent creatures would mean contending with these herds, the herds and the lands they occupy are left alone except as a food supply. Note that some primitive tribesmen could be included in this type.
- Destructive Wanderers are big monsters with a malevolent agenda. Exactly the sort of creature that adventurers are often asked to kill, as such creatures move into an area (often civilized) and begin to wipe out everything within reach, moving onto the next space once the previous space has been smashed. Such monsters are rare, temporary, but the destruction left behind can last a season or even a few years, depending on the monster involved.
- Builders include creatures who physically seek to constructively redesign the environment once they have entered. This includes most humanoids plus some odd creatures like beavers or giant termites. Fundamentally, the land itself is changed so as to provide obvious evidence that the land is occupied by something, producing trails, fields, buildings and altered physical features while also patrolling said area.
- Eradicators are permanent destructive entities that create a stable area of complete eradication of other life, so much as they are able. This would include many forms of undead and a few highly intelligent malevolent monsters who want an area of desolation between themselves and their neighbors. Such creatures are usually left alone, as entering the area of desolation often promises a terrible and early death.
From the above, we can propose covering a wilderness like a patchwork quilt. Most lands with semi-existent vegetation would be occupied by vermin; low vegetation grasslands or heavily vegetated jungles and forest would be occupied by passive wanderers; while anywhere with a water source and arable land would be occupied by a builder species.
Mixed in would be rare instances of destructive wanderers for player game service and hints of the existence of eradicators in the deep wilderness.
As players move through the wilderness, they can be informed of the probable inhabitants (through a ranger or druid's knowledge) by virtue of the amount of vegetation and livability of the topography. Trails could indicate passive wanderers or might be a hint of a builder. As a builder's territory was encroached upon, there would be more indications of environmental reconstruction (signs, hunter blinds, abandoned outposts or shelters, etcetera). Such signs can then be tailored for the specific monster that actually occupies the space.
Next we should talk about spaces and how to determine the size of a monster's territoriality.