"What do you mean?"
"Canines can't metabolize theobromine effectively."
Gavin patiently explained the science to Lupin.
"Even trace amounts of Methylxanthine build up in their heart muscle and central nervous system, causing fatal convulsions. If becoming a werewolf is a complete biological transformation of the body, then high-purity chocolate would be deadly poison to a werewolf while transformed."
"That's not what I'm asking—"
Lupin stopped what he was doing. The gentle smile vanished from his eyes.
His gaze lingered on Gavin's face, then snapped toward the firmly shut door.
Only then did he realize Gavin's repeated checks hadn't been to protect his secret. They'd been—
To protect himself?
The air in the lounge suddenly grew heavy.
"Why did you think to ask that?"
Lupin's voice was low and gave nothing away. He decided to make one last attempt.
"I suddenly figured a few things out. Then I saw this on the table when I came in, and it made me curious."
Gavin pointed to the chocolate beside Lupin's hand. Lupin used it to restore his energy.
Lupin lowered his eyes and gathered the spread-out sheets of parchment one by one. Striving to keep his voice steady, he said, "If you're interested in werewolves, I can recommend a few books. But you might not find the answer to such a specific question in them."
"That's why I wanted to ask about your experience."
Lupin's hands slowed. He looked up at him.
"Gavin, teaching Defense Against the Dark Arts doesn't mean I have firsthand experience with every dark creature—"
"You know what you've eaten, don't you?" Gavin interrupted.
Lupin watched him in silence.
"I mean," Gavin said calmly, "after you turn into a wolf."
One sheet of parchment remained. Lupin's fingers rested on it, but he made no move to pick it