Primal Companion Hunter and Evolutions

[Chess Pwn]

My question is with the Large evolution. When can I use it? Anytime, if so does it's size change if it was already large? Only when my animal's normal current size is Medium? What if the animal is under reduce animal spell?

[Calth]

If the AC is large already, the 4-pt large evolution does nothing. There is an option under the large evolution to spend 6 points to increase the eidolan(or ac in this case) to huge. I would say you can still do this. You would lose the ability score bonuses from the size increase from the large growth and gain the size bonuses listed for the huge evolution.