The Blind Side Character is an (SSS)-Rank Esper

Zephyr spent his entire life trying his hardest, only to be told that he was worthless. To his own family, he was nothing more than an embarrassment—a useless failure, a disgrace they would rather hide from the world than acknowledge as their own.

With his eyes gone, he had long since accepted that this was all his life would ever be. But everything changed when he awakened as an SSS-Rank Esper and met Lucien O'Connell. The man who became his salvation.

But Lucien knew something Zephyr didn't. He was nothing more than a side character who died in the original story.