The master you can talk to about anything.

Attributes: The student and teacher relationship has been a constant in society because institutional memory takes a lot of the pain out of being productive. If someone older and wiser knows what works and what doesn’t whereas you don’t, you should listen to them, obviously. But the master and student dynamic can vary in formality and it’s no surprise that an avatar known as The Close Mentor came about as masters and students who trust each other with knowledge and skill that defines them both form close personal relationships, be they friends, family or even lovers.

Taboos: The Close Mentor cannot hurt either his/her student’s progress or his OR his/her relationship with the student, unless it’s one at the expense of the other. In other words, you can’t not teach your pupil a technique or secret unless doing so would lead to you and him becoming more distant and you can’t foster resentment in him unless you’re trying to encourage him to train extra-hard when he should. Of course, you ideally want to hurt neither in the course of your teachings.
Having your pupil complete his training and move does not weaken your connection to the archetype, just as long as he still thinks of you as a trusted friend and teacher who helped him reach his potential in some way.
Close Mentors may have more than one pupil at a time, although the more students under your wing, the more trouble it is to avoid taboo.

Symbols: Obviously, symbols of your teachings (black belts for teaching martial arts, a textbook for academic matters, bottles of booze for dipsomancy mentoring, etc.) count. Even more potent are symbols of your relationship with your student, such as pictures of you two together, slogans of virtue you made him repeat and advice you gave him.

Masks: Pretty much any fatherly wise sensei figure from warrior-centric cultures work.

Suspected Avatars in History: Mr. Miyagi from The Karate Kid movies and Professor Dumbledore are good fictional examples of this avatar…and maybe some others. Greek philosophers of note probably had a Close Mentor, although opinions differ on just how ‘close’.

Channels:

1-50: Your pupil’s unique connection with you gives him courage and clarity when he needs it. With a successful Avatar: The Close Mentor check and a quick moment to encourage and advise your pupil, the next roll your student makes within a day that is related to your teachings gains a +10% shift.

51-70: You are both emotional and practical supports for each, cementing mental strength. You may use your Avatar: The Close Mentor skill in place of a Pyschoanalysis skill, both for use in pyschological triage and ‘therapy sessions’. Typically, this channel involves long pep-talks, comforting excerises and lots of affectionate gestures.

71-90: Emotion and logic blend harmiously as you dutifully lead your pupil down her path, helping her grow and learn. With a successful Avatar: The Close Mentor check, your student will gain an extra experience point if she spends a significant amount of time in a session training and bonding with you. At GM’s fiat, this experience point can only be spend improving skills related to your teachings or on healing injuries that she sustains in the course of learning from you or similar things.

91-98: In any situation where you and your pupil/s are co-operating with each other against an obstacle or opponent (like a fight…), all of you can re-roll ANY failed roll. If your student rolls against a skill related to your teachings during that situation, you also roll your own skill. If both of you succeed, your student’s success is upgraded to the next level (normal successes become matched successes, matched successes become crits and crits stay the same but the next roll your student makes gets a +10% shift).