The incoming footsteps proved to be neither student, nor any adult he particularly recognised, but the armful of papers and the general direction suggested he'd used the library. And security was a tiny bit tighter these days than it had been when he was in school, although not usually in obvious ways to the students. So an invader seemed unlikely. Especially one with an armful of parchment. He nodded politely.
Once they passed each other Charlie heard the misstep the man made, having narrowly missed it himself (that one had taken practice to get used to again) and winced.
"Out of practice with the stairs?" he asked as he carefully turned back around at the question. He gestured at the man to follow him. "Staff room is nearest," he said. He needed to keep a hand on the bannister to keep himself stable, but once they were done climbing the stairs he held it out. "Professor Weasley, Charlie," he said.