Here is an issue. Power. What is power?
Power is the relative strength level in comparison to the player. Or a justified order of statistics that makes the NPC fit the niche they were designed for.
Should a foes that was a threat in mainly a physical form, remain only a threat in that way? Or could they become as time goes on more of a mental threat?
If properly 'played' then no, they should be a physical, mental, and social threat to the PC if the NPC in question would actually use one, any combination, or all of those tactics.
But, what does this have to do with answering the question about how to advance them in relative power to the PC?
Should mentors only help out in a pinch?
No. They are teachers, peers, and role models. People the PCs should look up to, respect, or fear (depending on which way the character leans morally).
Mentors should not however be a crutch for the character to sponge off of or have the NPC do all their legwork for them because they have this 'handy dandy' mentor who knows everything.
But, again, how does this answer the question about advancing the NPC?
Depends. Opinions vary. My guess would be when the PC needs help
desperately and their mentor is the only person they're close enough to that can help them.
What does this have to do with advancement?
How long does it last? How does one help in this one way?
You're kidding right?
The problems with these sort of NPCs is that story tellers handle them better than players do and we all think in slightly different terms.
I gotta call "bullshit" on that one Catalyst. Storytellers are not the people who should be running players NPCs for them; they should merely voicing and tracking the NPCs activities. The NPCs should be fleshed out, and raring to go before the character is brought into play. Obviously contacts and NPCs met after play are different.
Players who do not know whether or not a mentor or other selected NPC would or would not help them in a given circumstance need to be beat with a stick because they apparently were not paying attention to the game.
But, how does this have anything to do with advancement?
What is cool by Dave, may be bullshit by John.
If everyone did everything my way, the world would be awesome. John will learn, or John will be eliminated.
But it certainly doesn’t help Ravenshire with his question about advancement of NPCs.