aging fruited beers, sours.

Fruited sour should hold up just fine for a few months.

 

I doubt you'll notice a difference after a couple months at either temp.

 

2 months is a pretty short window so you shouldn't have any issues, though things tend to age slower at colder temps so maybe the fridge is the better choice.

 

"a very nice bottle that I want to age for a couple months"
You answered your own question...sort of. If you want to "age" it, don't put it in the fridge. But for just a couple months, I don't think your are going to notice much of a change if any. I'm assuming you have already had this beer fresh and this is why you want to age it? Personally, if I were going to drink this beer in a few months, I would just keep it in the fridge. But then again, I don't know the exact beer you are speaking of and I am not totally clear on what your reason is for cellaring it (what change are you looking for?).