In the NEA’s data system, they have a computerized format of every Esper’s blood structure to determine if any Guide’s have a compatible enough blood structure to form Pacts.

“I’d like you to meet, Mr. Leon. Our Association’s Top Esper. As it happens, you two have a 90.2% match rate. As such, I’d like to introduce you two and have you sort out if you wish to form a pact.” The Director introduced.