Increased Familiar Size
Source: Mongoose Ultimate Feats
originally titled: Big Famiilar
You can take a larger animal, vermin or beast as a familiar.
Prerequisites: The ability to summon a familiar.
Benefit:
You can bind an animal, beast or vermin of medium size or smaller to be your familiar. The familiar ceremony works just as described in the class description, except the creature is not actually summoned and must be present and in your power (charmed, tamed or captured) and of a Challenge Rating equal to or lower than half your character level. Once bound, the new familiar becomes loyal to you, and gains all the benefits of a normal familiar, except it has no species-specific familiar ability; it does not grant you any bonuses beyond those common to all familiars.
You must dismiss any familiar you currently have before binding a new one and you cannot bind a new familiar until a year and a day has passed since your last familiar was killed or dismissed.
For example:
Bainard the 1st level gnome illusionist wishes to use this feat to bind a dire badger as his familiar figuring he can ride it into battle. However since dire badgers have a challenge rating of two, he can‘t do this until he attains the fourth level. He decided not to bind any familiar at first level, since that would force him to wait a year and a day for his badger once he attained fourth level.
Special:
This feat can be taken multiple times, and stacks with itself. For each additional time it is taken, the maximum size of your familiar is increased by one category, from medium to large, to huge, and so on.