It took three turns of circling the grounds for Al to remember that insanity was performing the same action over and over and expecting different results.
He stopped calling by then. He reached the area where the hedges and the grass weren't charred, sat down and renewed the warming charm on his feet and then recast the waterproof spell on his socks.
I hope this means that they were so scared of burning books, they ran far, far away from here where the soil no longer tasted of ash to them, he thought.
"Thank you," he told Severus, who followed Al silently, despite Al's invisibility or the lack of light. Al wasn't loud either: breathing and thinking didn't require making noise. Perhaps Severus went by smell when he followed like this.