The subject of this question is a Kitsune character under a permanent Enlarge Person spell. I have some difficulties to figure out how it will react with the two shape features of this character, which are the Kitsune Change Shape and the Fox Shape feat.
Kitsune Change Shape says:
Change Shape (Su): A kitsune can assume the appearance of a specific single human form of the same sex. The kitsune always takes this specific form when she uses this ability. A kitsune in human form cannot use her bite attack, but gains a +10 racial bonus on Disguise checks made to appear human. Changing shape is a standard action. This ability otherwise functions as alter self, except that the kitsune does not adjust her ability scores and can remain in this form indefinitely.
The Alter Self description says :
When you cast this spell, you can assume the form of any Small or Medium creature of the humanoid type.
For this one, I'm not sure this is RAW, but what seems to me the most logical is that the alter self effect would come first, resulting in a medium humanoid character and the enlarge person next, to give a large humanoid. Otherwise, the Change Shape would allow the character to ignore the enlarge person effect when taking a medium sized form.
The issue with the Fox Shape seems even more tricky as this one is not directly related to the initial size and implies to take the form of a tiny fox. Would it ignore the effect of the permanent spell, or would it result in a medium sized fox ? Or something else ?
Finally, if some of these transformations enter in conflict with the enlarge person effect, would there be an impact about the permanency ?