LORD. Patron's a little icky currently associated with the patraon, patraeon, patroon school of SEO. Sugardaddy?
I like this man/lady of the house thing. Another alternative, you make them work for the person's name. From one culture: Who is your master? Answers the other culture: I don't have a master, I work for Fal'nor. Fal'nor, what do you want me to do today? ^^Of course, with my suggestion you don't have a general word for the people you work for. I struggle with the same words for the same reasons. We also don't have an equivalent for master in Portuguese. We also only have "employer" and that's also too modern. So I usually go with "I work for Fal'nor" and never mention the word "employer". We also have "lord" but that's one step above master so that's not what you want.
Well I have a situation where one character is heavily envolved with social class. Starting with the "free"; serf- good folk; Goodman,Goodwife, Master/Missy- gentle folk; Sir/Dame, baronet, karl- finefolk [noble]; Lord, Jarl, Earl- royal; king/queen, archduke, sovereign earl, imperial prince- imperial, emperor. So Boss in a social level would change terms as one goes up the scale.
Of course this is acting as if this confusion wouldn't exist between a book's Characters. Think how much fun you would have with three or four characters. Each one who is thinking, a given statement written in a letter which included the word "Master" had a different meaning.
What about "Benefactor"? And then give them a title showing a little respect when referring to them by name. I like what @Drake GreenWood suggested with the "Goodman" or "Goodwife" George had long thought his current benefactor, Goodman Lewis, paid less then Sara's benefactor. But, a job was a job, and he had a contract with the man, so he'd see it through.
On the term Patron, I ran across this concept in a history book the other day, which reminded me of this thread. https://en.wikipedia.org/wiki/Patronage_in_ancient_Rome Apparently in ancient Rome, patronage was a relationship of mutual obligation that fell somewhere in between employer/employee and lord/vassal. This was much more common, and much more binding, than what you might expect from say a renaissance artist and their patron.
Like what @Rosacrvx said you may be able to get rid of the term altogether, assuming the culture is right for it. Stealing @Stormsong07 example it would go something like this: George had long thought Lewis paid him less than what Sara was given at her workplace. But a job was a job, and he had a contract with the man, so he'd see it through.
Since this is a fantasy world with cultures largely of your own making, I don't see why you can't come up with your own term. Maybe an abbreviation of master? Like ma'er pronounced more like 'mare'?
I honestly wouldn't complicate it too much. Rather than the words themselves, the way the terms are used and the situations in which they're used in your respective cultures is what will give meaning to them. As discussed in the thread, the word 'Master' could suggest a few possible relationship types. The situation is what will give it meaning in your story. A formal "Mr" or "Missus" would be enough to say 'in the employ of' in the right situation and it might be more realistic (I know it's fantasy) if different people use different words for 'boss', depending on the kind of society you have and the different kinds of jobs you write about. Would artists use the same word for their employer as a security guard would? Would a paid servant use another?
