Espers are people w/ supernatural powers. When they use them on dangerous entities, their powers have a huge toll on them, physically and mentally, and Guides have powers that can heal Espers w/ physical touch.

"The results came in. Our compatibility for our powers is at 97%." Levi scowled. He hates Guides. He's the strongest, he doesn't need a Guide... At least he thinks. Levi never had a Guide for years, always sucking up the side effects after missions. An avg compatibility was 60%..