Bill looked up as he heard Al speak, smiling at him and curiously looking at the Peter guy he was introducing. "Advanced Arithmancy knowledge is always welcome," he said, though his eyebrow raised when Al mentioned he taught it. Pettigrew. He wasn't sure he trusted him, actually he didn't, but he supposed he too needed something to do.
"Nice to meet you," he said, gesturing to the chair. "So how much of an expert?" he asked. He was quite young, expert was probably a stretch.