Sharing Parma?

If a Magus shares his parma with a mundane noble, and then events cause him to cast a mind control spell on that lord before he can drop parma, does the shared parma prevent its caster from casting magic on its sharee?

Thx.

SJE

Yes.

Assuming that your Penetration is insufficient to Penetrate the Magic Resistance that the noble gets due to the shared Parma.

Note that a magi's Parma also blocks (baring sufficient Penetration) an attempt by him to cast a mind-control spell on himself (or any other spell). Unless he either suppresses his Parma or the Range of the spell is Personal.

Having said all that, although you need to Concentrate to suppress Parma, it seems that a magus can cancel sharing Parma "at will". So, I'm not sure that the precise circumstances you suggest are likely to occur. However, the same question arises when you want to cast spells on somebody you are sharing Parma with, but you don't want to drop the shared Parma due to the presence/fear of other hostile magics.

That would also apply to familiars, or are they a class apart?

Assuming you mean your own familiar?

Then all your spells should need to penetrate, but you'll never be without an indefinate duration AC to your own familiar (since you are that AC), for a x4 multiplier on penetration.

As for effects in the familiar bond, I believe there's an exception, but Noble's Parma on that!

Anyone sharing Hugh's parma will have a parma score of 0 which will stop me giving them the creeps but it's not going to do much against Hugh's mind tricks - he's good at them. In any case, I had left the room before Hugh neuralized Simon de Montford.

Familiars are a class apart, see AM5 p. 105, the Familiar Bond:
"Neither [master nor familiar] needs to overcome the other's magic resistance in order to affect them with a spell or magical ability".