How does Frightful Aspect work for a creature that is already large?

Question

I'm a druid and I have the Improved Spell Sharing feat, which allows me to share spells that have "you" as the target. I'm considering using the Frightful Aspect spell on myself, which if I do, and I divide my spell between me and my animal companion, then we should both get the benefits of the spell. The only question I have is that while it would increase me to the size of large, my animal companion is a big cat that is already large.

The spell:

You become a larger, awful version of yourself. You grow to size Large, and take on features that horrify your enemies. You gain the following abilities: a +6 size bonus to Strength, a +4 size bonus to Constitution, a +6 natural armor bonus, DR 10/magic, and spell resistance equal to 10 + half your caster level. You also emit an aura that emanates 30 feet from you. Enemy creatures within the aura are shaken. Each time a creature shaken by this aura hits you with a melee attack, that creature becomes frightened for 1d4 rounds, though at the end of that duration it is no longer affected by this aura. The aura’s effect is a fear and mind-affecting effect.

Should my large animal companion become huge, or does it stay large? There seems to be conflicting text because it says that I would "become a larger" version of myself, and that I would "grow" but then it just says "to large."

Curious to know how you'd all rule this. This could be important simply because it would affect my AC, CMB, and CMD, area of AOO, and other size related things.

Answer 1

Your animal companion stays the same size.

Compare the wording of Frightful Aspect:

You grow to size Large, and take on features that horrify your enemies.

To that of something like Animal Growth:

This alteration changes the animal's size category to the next largest

Or Enlarge Person:

This increase changes the creature's size category to the next larger one.

And finally with Alter Self:

When you cast this spell, you can assume the form of any Small or Medium creature of the humanoid type.

Unlike Animal Growth and Enlarge Person, Frightful Aspect (like Alter Self), sets the size of the creature it is cast on. Since it is already that size, it's size does not change (although it still receives the other effects of the spell).