Retainers are earned through your Primary class abilities. This means that each Hero class gets access to only one category of Retainer, and only one can be equipped at a time. Lords on the other hand get an entire Class-Gear set from their secondary Lordship class, meaning that they will will eventually be able to equip both their primary class Retainer and a Butler at the same time. 'Crafting' an item of Retainer gear requires Bread and some other appropriately sustaining good, but it's assumed there's a secret organization maintaining a standard of training for each retainer type. Their exacting standards that keep Retainers the same in every settlement also refuse to hire out to characters of too low a level. Their mysterious qualifiers will keep players working to earn the privilege of hiring a personal servant to tend their needs.
Bodyguard - By the time a personal Bodyguard will work for you, you're already such a badass it might seem silly. On the other hand, you're an important person with big awesome things to do. You could benefit from a personal assistant and it would be foolish to hire one who can't defend themselves. By literally being able work for and shield you, they raise your effective Toughness and Might. These loyal retainers require only Meat and Bread to train and sustain them throughout their service to you.
Valet - Your valet is there to ensure that you don't look like a fool in public. They know that your mind is busy making decisions that will effect nations and no no longer have time to keep your collar tidy and remember which Heroes belong to which local Ministers. Their gentle tending of your great person will make your Charm and Guile attributes more effective. These are very useful retainers who love to make you look good.
Assistant - The Primary-Traders get their Assistant earlier in the leveling process than other classes. This may be because their natural skill set involves being a good employer that the organization of Assistants allows themselves to be hired by such inexperienced players. Every assistant makes your business their personal concern. If you choose to keep one in your retinue, they increase your Acumen and Arithmetic attributes. In order to 'craft' and 'upkeep', all they demand is Beer and Bread.
Secretary - The Secretary is a quiet, unassuming soul. Once they allow themselves to be hired, they are putting their lives and reputations into your hands. They are with you always, keeping your records and notes and helping you tend your vast spiritual flock. All this care allows you to make better use of your Fervor and Philosophy and require is reasonable pay in Silver Thalers and Bread.
Astrologer - Your personal Astrologer is there to enhance your immediate local spiritual knowledge. With them at your side all day, you can know what the 'stars' have in for you at any moment by demanding an on-spot reading. Forcing them to branch out into auguries and logic will further enhance your Creativity and Judgement, but they require a constant supply of Glass with their bread.
Butler - Every Lord eventually is allowed to hire their own Butler. Whether you have your own estate or are renting a room, you may eventually rule something and have to keep up appearances. The butler's association will gladly provide you with a butler based on availability and your personal price-range. They do of course cost both regular Bread and discreet stacks of Gold Florins These helpful retainers increase your apparent Judgement and Oratory attributes by always being there to support you.