Yosharian
Arcane
Hmm. Well I definitely remember not being able to buff for this fight, I was drawn immediately into dialogue so I had to reloadAfaik, Aeon has two variants of encounter with Meph - you either agree to meet with him at marked location or he will catch you en route on the way to Kenabres. In my version, with agreement, I had prebuffed before talking to him without any issues.Aeon doesn't have time to buff either. But, I managed to buff anyway.
I also had no issues prebuffing when playing Azata - you need to approach him and free crusaders close enough to trigger the scene.
I probably told him to get fucked in the previous conversation