Medium Dire Rat Animal Companion

[trollbill]

I have a 3rd Level Halfling Ranger that wants to get a Dire Rat animal companion at 4th. I would eventually like to use it as a mount. Problem is, Dire Rat animal companions don't change sized when they advance, so they always stay small. Animal Growth would work but it only last 1 minute per level and Rangers can't cast it until 13th level anyway. So is there any PFS legal way to make it medium on at least an adventure length basis?

[Nefreet]

Couldn't you just drink a potion of Reduce Person?

[BigNorseWolf]

Still 1 minute per level.

I don't know any way to do this.

There is however technically no rule preventing the mount and rider from being the same size. (a mount class feature must be one size bigger). You might take a -5 from an unsuitable mount though

[Nefreet]

Take 1 level of Sylvan Sorcerer and cast Enlarge Person on your Dire Rat via Share Spells.

Still only 1 minute/level, yes, but it's an option.

[FLite]

It looks like Giant Weasel is your closest viable option. (Well, goblin dog, but in pfs you need a goblin boon for that I believe.)

[Ellias Aubec]

You could look at getting a wand of Animal Growth.