Some of you may not be aware of the origin of the Dosem in other works of fantasy -- I know I wasn't when I first began playing Lys, and that has worked to my advantage. I am told that the Dosem of GvE, as established through Lys and other player characters, are quite different from their counterparts.
What follows is usually a difficult question for me to answer, and this text is as much for me to sort out my own thought as it is to pass them along. Most of what you'll see in here are references to the Dosem history and their interaction with other cultures, as I have interpreted it. Players interested in playing Dosem characters should also consult the companion piece to this one, "Reflections on the Wandering Souls", where you'll find role playing suggestions and tips.
The Dosem, as they are established in the Dosem Mythos, are a peaceful, agrarian race that is largely isolated from the rest of Thistledown, presumably by terrain features or simply being remote from any established empire or other settlement of the time. (Their current concentration in Loamburrow is not necessarily where their civilization was established.) This is a key building block for the Dosem's ability to "piss people off", as it has been put to me. Being isolated, early Dosem have not had the years of tempering in contact with other cultures that the humans, elves, orcs, and other lesser races had at the time.
At the time of the start of the Mythos, Dosem social conventions, when compared to other cultures, are quite different. What is considered rude or even means for a duel in other cultures are the norm in Dosem society - a burp is a compliment to the chef, a yawn isn't something to be hidden behind a hand, etc. Among themselves, Dosem get along rather well, as they are well adjusted and living in an open, friendly society. Much of what governs their culture at the time can probably best be derived from the current state of Wellhaven -- authority is loose, and heinous acts are almost unheard of.
The revelation that the Dosem are not alone on Thistledown, and of the events that led up to Gaelsam's adventure (and the adventure itself of course) likely marked the first occurances of social interaction between the Dosem and other cultures. Gaelsam's success in encouraging the Walkabout came at the cost of social interaction that was the equivalent of throwing cold water on heated thin metal. Gaelsam himself doubtlessly had issues while on his adventure, though the Mythos tends to quietly slip these problems under the literary rug.
Given the events surrounding the climax of Gaelsam's adventure and their sudden appearance in the world, it is also understandable that other cultures themselves were mistrusting of the Dosem at first. There is some evidence that at least one empire on Thistledown briefly considered the Dosem as the defeated remnants of the enemy army, or their cursed servants, and some settlements went so far as to accuse the Dosem of being the agents of evil forces. Once formed, stereotyped opinions are often hard to overcome, but as the Dosem continued to spread across Thistledown, people began to see the Dosem in better circumstances as their society transformed from a compact agrarian culture to a far-flung network of traders, tinkers, merchants, and practicers of a variety of working trades.
The Dosem have themselves adapted. Many speak Common as their chosen language, though most remain bilingual. The Dosem language itself has adapted some frequently-used Common words as well. Though the Dosem are very much considered "raunchy" and "uncouth" by other cultures, each newer generation tends to adapt more conservative behavior in front of other cultures. Indeed, many Dosem who have been Walkabout for some time have become skilled in containing their Dosem tendancies in front of others, though they often quietly complain of being bored or feeling 'boxed in.'
However, the Dosem seem to demonstrate a seemingly genetic trait of outlandish behavior, perhaps in spite of the need to "restrain themselves" in mixed company. Visitors to Dosem settlements often find themselves completely overwhelmed by the social barbaratry that the Dosem demonstrate, to the point where some travellers will continue travelling in hopes of finding more hospitable company. That said, the Dosem have found that after others complain about their behavior, a complaint about low doorways is soon to follow, except from fellow halflings.
Thus the social friction between the Dosem and other Thistledownian cultures can be summed up as being in part complications from the initial meeting of these cultures, and in remainder the incomplete assimilation of the average Thistledownian moral and behavioral definitions into Dosem society.