Having spoken at some length previously on the playing of characters in non-adventurer roles, and having my own example in the Knights of Miles and the Imperial Schola, I think it is safe to say that most non-adventurer style positions that still manage to participate in the sort of activities common to adventurers tend, at least in a truly medieval setting, to have the requirements of obedience and the following of strict rules. We can discount, for the purposes of this post, normal servants found in urban households as well as artisans, as these do not generally make good player characters without DM intervention (ie, manipulation of the story on a meta-level agreed to by all present players in order to extricate those characters from their social setting, at which point what even is the purpose?)
SO, the thing we really need to look at, then, is the profusion of servants in the Middle Ages that might well provide players with an idea for a PC. Additionally, those PCs who are socially integrated (whether at the beginning of the game or, as is much more normal, once they reach name level) should avail themselves of many of these types of servants.
Servitude is a major part of Medieval life. Even the nobility must be servants in their youth, albeit to those of greater rank, saving only those at the very top of the chain. Even counts and dukes served as cupbearers to the king. Simply knowing the vast number of servile types (and which were appropriate for promotion to more adventuresome careers) would go a long way to making an AD&D game richer and more interesting—and, as a side-effect, more strongly medieval.
There are any number of duties that we do for ourselves throughout the day that would be taken up by the activities of servants, particularly in a noble household.
Pages & Military Servants
As a category, these are very likely to entail some kind of adventure-related activity. Many of these servant types could also be the children of nobility, making the option to play a noble more viable since one would have to go through a period of servitude first, thereby "earning" increased status and "balancing" increased income against the social services one is bound to provide. They include:
The Page. Noble boys, beginning at age 8, would leave their parents and serve as a page (an apprentice squire) in a household. Pages served a more general role than squires—running around, bearing messages, cleaning armor, etc. Around 13-14, a page would be expected to become a full-fledged squire, having learned how to ride, hawk, hunt, etc. A knight or lord might have any number of pages apprenticed to him. These servants make great all-purpose hirelings.
The Squire. Older than a page, beginning around 14, squires serve as apprentice knights. Squires generally bore armor and weapons (a particular type of page or squire would be the sword-bearer, who carries his lord's weapon in its ceremonial sheath), banners, and other such things for their lords. They also fought alongside their masters in battle. Once again, a perfect hireling type OR a perfect starter for a noble character. Squires usually come in groups, serving a single knight, who could be an NPC.
Knights. Knights generally served a lord and thus would make up the elite fighting force of lordly PCs. PCs probably shouldn't start play as full fledged knights, as this grants too many resources at the beginning of the game, however I suppose it could be done—they'd have a small cluster of squires and a flock of pages of their own, which could serve as a mighty retinue of hirelings.
It's important to note that pages and squires don't get an income beyond their clothing, food, and board (which can tally to a pretty penny). Regardless of what the AD&D 2e DMG says, most feudal servants do not receive pay as long as they have been asked to serve for longer than their 40-day summons.
Fighting Men or Men-at-Arms. Though the term man-at-arms refers almost exclusively to Renaissance knights, this term has come to be applied (at least somewhat casually) to the peasantry who were drafted for temporary military service at local castles. They may also include mercenary garrisons at heavily defended and garrisoned castles (which would indeed have to be paid). These fighting men perform a generally servile role in that they would be commanded by a castellan, gateward, or other such fellow, but might serve as a good beginning for a whole group of PCs.
While the great majority of servants in a medieval household were of a military function, there were some who did other things as well. These are almost universally unsuitable to be player characters due to their lack of involvement with or skill in combat. IF, however, players are looking for a particularly difficult level 0 challenge OR are willing to play such characters as thieves or fighters of low level, there COULD be a great deal of non-traditional roleplaying opportunities to be garnered from so doing.
Kitchen Servants. The chief cook, undercooks, butler (head of the buttery, ie. larder and wine room), scullery maids, and kitchen boys constitute a whole rank of servants in themselves. These would best be represented by level 0 folks or thieves.
Hawkers, Hunters, and Gamekeepers. Hawkers and Falconers are dedicated to training and maintaining a lord's falcons; hunters and gamewards/keepers assist the lords in their hunts by managing hounds, beating the brush to flush out game, and to keep certain forests stocked with huntable animals like stag and boar. These servants would be interesting fighter-classed people (even if they started at level 0, though there's not necessarily a reason why they would).
Ladies in Waiting. These are for the reigning lady of the house and her children, particularly the girls. They have almost no input in the day to day life of a medieval household. They might be interesting as sorceresses or thieves. They're mostly maidens who spend their days reading, sewing, and philosophizing.
Miscellaneous Servants. These are what we think of when we think of "servants." Even so-called middle class households would have at least one servant to fetch water, start fires, etc. Good hireling material. Difficult as hell to conceive of as material for a PC.
Administrative Servants. These are things like Seneschals, Chamberlains, Stewards, Maior Domos, etc. Being mostly jobs concerned with resource management, tax collection, etc. These are not very well suited to PC positions, but for the ease of managing vast estates and many servants they make great hirelings and henchmen.
Stay tuned for ideas on PLAYING servants and people who begin in a servile role.