What business do a man, an elf, and a dwarf have traipsing the countryside looking for quests? Where do they come from, and how do they fit into their society? Can they exist at all? I'll give a few answers to these questions below.
Let's be clear that socially untethered, do-gooding "adventurers" never existed. In medieval Europe, there were many kinds of travelers, from tinkers to mendicant friars, but these were not heavily armed members of small gangs. There were mercenaries, and this is likely the best model to follow. But it is not perfect: mercenaries were soldiers employed in war. They weren't used as go-to problem solvers, and they didn't include non-fighting men.
Even taking a mercenary band as a starting point, our adventurers will have some serious trouble in a real society. To accommodate them, we'll need either to change the world away from reality, or change our adventurers away from the norms of fantasy.
1. No one trusts an adventurer
A group of adventurers wandering into a town, on an errand known only to them and with a willingness to solve local problems, is highly troublesome. This is roughly equivalent to a cavalcade of black SUVs pulling into your town, with kalashnikov-toting thugs poking around and asking what ails you. What would you do but shut your door and call the police?
A medieval peasant, or even towns-person, is far less worldly than you and probably even more defenseless. Armed strangers are assumed to be robbers. Even "legitimate" mercenaries could easily turn to banditry if they didn't have work, so could never be trusted, and were also rough, unruly men -- not the sort you want hanging around. So any village leaders are unlikely to welcome your party; and if they're pressed to house you for a night, they'll do so with great suspicion.
1a. Local lords are jealous
Armed, wandering adventurers are a direct threat to any local power, whose identity is inherently military. Depending on what time and place we're discussing, the local government could be little more than a small-time warlord with a rough band of men. Adventurers who traveled without their leave would quickly find themselves challenged -- indeed, suspicious villagers would probably see to it.
Forget any do-gooding and friendly receptions. Have adventurers work on the margins of society and be ill-regarded. They will have to be inconspicuous and often flee from established power.
Give the adventurers a well-regarded and stable role in society, besides a mercenary one. If they are approved of by a religious order or king, they could be acceptable throughout society. But this means they have a recognized job to do, rules governing how they do it, and someone to answer to if they fail.
- Make "adventuring" a common activity endorsed by rulers, and thus familiar to every peasant and blacksmith. How? There should be some physical threat that is constant but dispersed, making large organized forces an inefficient way of dealing with it. Elites will probably regulate (and tax) adventuring activities, preventing the main characters from being very anonymous. The flavor of your game would change a lot from the norm. Some scenarios: A new frontier region has opened up, and is infested with monsters. The crown pays adventurers bounties, to ready it for expansion. Of course, we are invoking a rather unpleasant parallel with colonialism. Central authority is weak or occupied, and nearby enemies regularly send raiding parties to steal livestock and burns villages. Adventurers are basically war-time privateers. ** Monsters are an everyday part of life, emerging from the ground or thin air, to trouble villages and towns alike.
2. Peasants don't have swords
In the middle ages, much like today, weapons and the other gear of war is extremely expensive. A warhorse, in real terms, cost as much as a Corvette today; armor nearly as much; a sword thousands of dollars.
Even with the money, there was nothing like "ye olde armor shoppe." Swords and armor are produced by special smiths, often working directly for lords in official armories. Even if independent, they didn't have shelves of equipment laying around for purchase. Realistically, any kind of adventurer would need to have significant wealth and social status before ever setting out: only this could give him the tools he would need (and this equipment would, to some extent, broadcast his stats).
This means an adventurer who rises from the lowest levels of society, economically, is unlikely. Peasants could of course turn outlaw, but petty outlaws are not likely to be kill or rob anyone with weapons to claim. Even if he acquired money, a peasant is in a poor position: While civilians can legally buy weapons in the US, not so in most of medieval Europe. A person of obviously low birth walking around with a sword would essentially be admitting to outlawry.
Make weapons a far more common part of everyday life. This would probably not be tolerated by lords unless warfare were endemic or some supernatural threat required their peasants to regularly see to their own defense.
Take your adventurers to be socially well-off. Second sons of lords might get no inheritance and thus be forced into service as knights or mercenaries.
- Imagine some difficult paths for social advancement in your world, and force characters to have such a thing in their back-stories. Perhaps the population is low and lords with too few men find the best fighters in the peasant militias and elevate them. Or imitate the Ottoman Empire's janissaries, who were claimed as part of a "boy tax" from every town, and trained as the royal guard.
(This is the first installment in a series. You can read the introduction, with links to all relevant entries, here.)