So, after some consideration i’ve decided to give the Familiar a fun high level upgrade, which originally belonged to the Mage Knight Prestige Class, which is currently being redesigned and cut down to a 5-level Prestige Class.
The Familiar’s ability development have been moved around and reordened to all uneven numbers, and 2 abilities have been added: Familiar Spell Slot, and Familiar Caster. These 2 abilities allow the Familiar to utilize it’s growing intelligence to first contain a spell slot that can be used by the Sorcerer/Wizard as a prepared wizard spell, and later (lvl 17) the Familiar will be able to independently cast the prepared spell they contain.
It’s a slight shift of power to the familiar at higher levels, making a straight up Sorcerer or Wizard career even more appealing, without causing to much disturbance in power balance.
The Base Classes PDF has been updated.