Fawkes is a phoenix, Harry. Phoenixes burst into flame when it is time for them to die and are reborn from the ashes.

“Because - oh shut up laughing, you two - because they've just been turned down …”

“Well, hello, Peter,” said Lupin pleasantly, as though rats frequently erupted i…”

“No witch has ever claimed to own the Elder Wand. Make of that what you will.”

“To the Dark Lord,I know I will be dead long before you read this but I want you…”