Yesterday I was rolling the crisis for some NPC of the saga when one longevity potion failed miserably. The magus los a point of Perception. Now, he has a hawk familiar, and the question is if the familiar should roll for a crisis as well, or lose the same point of Per. Do familars age or are they unaffected and fitt as long as their magus is alive?
With nothing on hand to back me up, I'd go with the familiar ages as the magi, but can't die from old age as long as the magi is alive. Of course depending on how foul a mood i'm in I may be convinced that familiars can die of old age...could make for a good story
I think it works better seeing an old wrinkled magi and his equally aged familiar rather than a young fresh familiar.
I'm surprised that more players don't take the Unaging Virtue (page 50).
(minor , supernatural)
In opur group it was so common that we house ruled that you could only take it if you had 2 more minor supernatural virtues or a major supernatural virtue. Otherwise it was getting silly. Quite like the gentle gift in our political 3rd edition saga, really.
In any case, this is NOT a player character, but an older chap that appears regularly in the saga and so has a full character sheet.
EDIT: On familiars.... it seems weird to see the aged and crippled magus with his radiant, active and playful dog/eagle/cat/whatever familiar.... at least to me.