Oh dear Merlin. If there was one thing Percy didn't know how to cope with, it was a crying woman. Especially one that was incredibly like his mother.
"I– um– well, you see–" It was a rare occasion that Percy didn't know how to answer a question. His mind staggered around, searching for something reasonable to say even though everything about the situation they were in defied all reasoning.
"We must be from different times, you and I, because Harry has grown into an excellent wizard." Perhaps that would comfort her!