aeons are the physical realization of the fayth’s dreams. The fayth communicate with summoners who pray to them within the Chamber of the Fayth, and establish a mental link between the fayth and the summoner. Using this link, the fayth gives their dream a physical form — an aeon. Aeons are powerful creatures only a summoner can use in battle.
We destroyed our own allies. We destroyed the aeons who had fought together with us, at our sides. We didn’t have a choice then. We believed that was the only way we could save Spira. Do you know what it felt like to watch them die? Right before my eyes? It was the only thing we could do. It was the only choice we had. I gave in, I accepted, I believed. I allowed it to be true. I thought I’d be able to go through with it without ever doubting myself. But I… It hurt so much.