Dumbledore had Fawkes deliver a message asking Miss Walker to come to his office. Just before Miss Walker arrived, Mr. Grindelwald transformed into his disguise as Mr. Green.
Snape, worried about Miss Walker after seeing the message, had accompanied her to see Mr. Dumbledore. Upon entering, he caught sight of Mr. Grindelwald and Mr. Dumbledore. Snape paused for a moment, mainly because Mr. Grindelwald's gaze was far too intense. Searching his memory, Snape was certain he had never met this man before, yet the man was looking at him with a strange yet strangely familiar expression.
"Mr. Dumbledore, why did you call for me? My teacher happened to be with me, so we came together," Miss Walker spoke up before Mr. Dumbledore could say anything.
Chapter 25