Linguistinc one-off

Just a quick thing I'm struggling with in a future, much longer, entry I'm working on.

Parent:Child::mentor:?

What's the opposite of "master" where the answer is not "slave" (such as: in martial arts, or chess, where rankings are formalized).

The terms "student" and "pupil" don't feel right. I'd use "padawan" if I didn't think it made me seem like such a "dork".

I need a generalized term for people I care for, offer advice to, consider giving collars to, but who are not necessarily submissives or slaves. I've taken to using the term "underlings" but that feels a bit like "small scurrying varmints". I occasionally use "subs" but mention that it's an ambiguous term that can refer to both submissives and subordinates. I occasionally use "pets" but as I formalize things, that too seems like it implies something physical/sexual/dominant that may not be the case.