This was posted by Epona in another thread - to Bahamut - and she has tested it out and it works! I have not tried it myself:
As far as I know it is possible for ANY character to have a familiar, but only using a great deal of cheese by exploiting a game loophole, as follows...
Pause the game.
Go into inventory, and empty all items, INCLUDING quick slot items, except one find familiar scroll and one useless potion (a small healing potion for example).
Select the potion and select 'drink potion' - you will hear the gulp sound.
Pick up the scroll and put it in the slot where the potion is - drop the potion on the floor (not in another inventory slot).
Go back to the game and unpause.
The graphic you see will will be the little twist of smoke as if you were drinking the potion - but the spell will be cast instead.
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