I think you're thinking of a master and apprentice (albeit through the lens of a world which resembles that of Westeros...) In any event, not the mentor relationship the OP was inquiring about.
You know, I don't think so. Trades have been around for a lot longer than universal justice. Slavery is only recently going away. Important people in the community have traditionally done what they wanted and as long as it wasn't too egregious, they usually got away with it.
A little light googling turns up no shortage of cases of apprentice abuse, (including sexual) from the relatively recent past (1600's on... a time that is comparatively modern in the "objective" dispersal of justice). One can only imagine what earlier times were like. No doubt there have been plenty of beneficent individuals, but the beneficent treatment of fellow humans is sadly often the exception historically speaking. For most of human history there has been a very different standard of what was acceptable than we hold today. A third party flogging for failing to follow orders (or simply because the flogger was having a bad day) likely scarcely raised eyebrows as long as it didn't get out of hand for most of human history.
Even today we still see remnants of this relationship. Abuse of underlings who put up with it because they think it will get them somewhere. Taking on an "apprentice" out of sexual interest rather than simple interest in their development. Human nature has not changed terribly much... just the rules.
I don't know what kind of relationship OP is after or what he is willing to do to get it. I do wish him the best of luck on his quest.
