Delaney

The disc was slowly rotating, a ring of brighter white light flowing around its edge and emitting a steady low-frequency hum.

Delaney stood beside the disc with his back to the door, looking down at it with a long, pen-shaped object in his hand.

It appeared to be some kind of magic detector, its tip pointed at the disc's surface as though it were reading data.

Hearing the door open, he did not turn around at once. He merely stopped what he was doing and slowly turned to face them.

He looked at Harry, then Hermione, then Ron. His face showed little expression, and his gaze was calm, as though he was not surprised to have been discovered. It even seemed as if he had known they would find this place sooner or later. "You're faster than I expected."

"What are you doing?" Harry asked.

Delaney lowered the detector in his hand, but did not put it away. He simply held it with the tip hanging toward the floor. "Measuring node fluctuations. This spot in the South Tower is close to one of the castle's Ley Lines convergence points, so the energy flow here is more active than elsewhere. The pipe system beneath the abandoned bathroom also leads to the same Convergence Point. I thought that if I got precise data, I could determine how frequently this Convergence Point was used."

"Who are you measuring for?" Hermione asked.

Delaney fell silent for a moment, as if considering how to answer. "For myself. I'm working on a research project—on Hogwarts' ancient Ley Line structure. I read some materials in America saying that Hogwarts is one of the few schools in Europe built on a Ley Lines convergence point. My exchange student status is real. I really did come from America, and