Summoner

A thousand-year-old broken tradition that lets summoners walk toward their death for Spira's hope. Summoners are practitioners of a sacred art sworn to protect the people of Yevon. Only a chosen few become summoners: those who can call forth entities of great power, the Aeons. Yevon teaches that the Aeons are a blessing.

Lady Yunalesca was the first person to defeat Sin. She chose her husband, Lord Zaon, as the fayth for the Final Aeon. There must be a bond between the chosen one and the summoner: a bond between husband and wife, mother and child, or between friends. The bond should be strong enough to let its light conquer Sin. But once the Final Aeon is called forth, the summoner's life will end.

And Sin will be reborn.

Summoners embark on a pilgrimage, a long journey to Zanarkand to obtain the Final Aeon from Lady Yunalesca. They defeat Sin and bring the Calm, a time of peace, even if only for a while. To the people of Spira, it is worth it. For a short time, they do not have to be afraid that Sin will destroy their homes or kill their loved ones.

Before Lord Braska became a High Summoner, a half-Guado boy named Seymour was already gifted in manipulating pyreflies. The Guado possess the power to summon fiends onto the battlefield.

At the age of ten, Seymour travelled to the Zanarkand Ruins with his mother to obtain the Final Aeon, so that he could be accepted by the people of Spira. His mother loved him, but the world made love into sacrifice. Sacrificing summoners was, for Spira, their only hope.

This line matters to me. It suggests that Seymour was really planning on using a summoner, trying to force the bond that was necessary for the Final Aeon, so he could become Sin.