Shiina, the forgotten gift.

While cults of the SEER looked to capture every last one of those with a gift, one was left out. She was recuited at young age and had to undergo the "treatment", hence the missing eye. But she managed to flee without a trace and escape from the cult's controll.
They worship and train the most powerful of the gifted while "harvesting" the rest. But her gift was the greatest, so after she disappeared the new oracle had to be second choice. Already scarred and torn by the torture.
A weak oracle is nothing but a puppet and a tool. Used to apease ones followers and to .... "porduce" another, more powerful oracle...