... for a person who is in the belowdescribed relationship with a
scion of a noble or wealthy-and-socially-prominent line:

["the person" below refers to the person for whom I am seeking a term.
"the scion" is the individual of noble blood who is the 'principal' in
the relationship]

When the scion is young, and perhaps still in school (even before
majority), the person serves as a bodyguard, advisor, and tutor, but
most of the learning that the person imparts is that of experience,
rather than pure academics - he will allow his charge to get into
trouble, and then *assist* him in getting back out, while explaining
how the trouble came about and how it could have been avoided.
Bodyguarding is not protecting him from *all* harm, but from threats
that could impact the Family - if the scion provokes a bully, the
person will not prevent the scion from having to take his lumps - but
will tend any wounds afterward, and will offer to teach self-defense
and non-provocation (where appropriate).

As the scion gets older and more mature, the person will continue in
all the roles described, but shifting more toward an advisor role, and
gradually adding the role of 'facilitator' - when the scion moves to
do something that this person sees as beneficial to the Family, he
will do what he can - subtly - to promote the activity and elicit
cooperation from others. In the advisory role, even if the scion is
proposing to do "the right thing", whether by ethics, morals, Family
benefit, etc., the person may argue against it, to get the person to
clearly realize his own reasons for doing/proposing it.

It is likely that the scion will come to view the person as a
'friend', though never as a 'lackey' - even though the scion has the
'social advantage' (i.e., higher status), the nonpublic relationship
is far more equal, and quite often, the scion will specifically turn
to the person for advice. Equally, the person will involved with the
hiring of the scion's personal staff, and will often guide new staff
members in their understanding and response to the business/social
needs of the scion.

[For those of you who have read the Jao Empire series by Eric Flint,
K.D.Wentworth, and David Carrico, the Jao word for the role is
'fraghta'. I want to more-or-less have this role available in a
generic Traveller universe - but I don't want to use the Jao word for
it; I'd like a human word. In any language.]