Muggles' Guide to Harry Potter/Characters/Armando Dippet

Overview
Armando Dippet was the headmaster of Hogwarts before Albus Dumbledore. He is a wizened and frail-looking wizard when we see him, bald except for a few stray wisps of white hair.

Chamber of Secrets
Here, we see Professor Dippet only through the memories of Tom Riddle's diary. Tom is requesting permission to stay in the school over the summer; Professor Dippet turns him down, saying that the attacks on the students have made that quite impossible, and if they do not cease he may have to close the school down. In the Chamber of Secrets, Tom Riddle mentions Professor Dippet contemptuously in passing, saying that Tom was able to fool him easily, but was never sure that Professor Dumbledore was fully convinced.

Order of the Phoenix
Professor Dippet is one of the portraits hanging in Professor Dumbledore's study. Shortly after Arthur Weasley is attacked, just before Christmas, Dumbledore needs the portrait of Phineas Nigellus Black to carry a message to Sirius Black at 12 Grimmauld Place. Phineas Nigellus feigns tiredness, and many of the other portraits in the office are outraged; the portrait of Dippet, in particular, is angered, saying that they are sworn to serve the current Headmaster of Hogwarts.

Half-Blood Prince
Professor Dippet's portrait in the Headmaster's office does say a few things during the course of this book, and it is mentioned that Tom Riddle had approached Dippet upon his graduation to ask for the post of teacher of Defence Against the Dark Arts. Dippet had turned him down, saying that he had not yet had enough experience, that he was as yet too young.

Deathly Hallows
When Harry is in the Ministry, looking through Dolores Umbridge's office for the locket, he happens to see a copy of Rita Skeeter's book about Dumbledore. On the cover, it is noted that she is the bestselling author of the book Armando Dippet: Master or Moron?

Weaknesses
From the little we see of him, it appears that Professor Dippet tends to favour some students, notably Tom Riddle. While his ignorance of Riddle's true nature could be seen as evidence of gullibility, we note that trusting Riddle seems to have been very common in that day; the young Riddle apparently was quite personable.

Dippet did ignore warnings from Professor Dumbledore, who was then Transfiguration master, concerning Riddle; but Dumbledore himself suggests that he was one of a very few who saw Riddle's true nature.

Analysis
From the limited number of times we see him, it is hard to get much of a feel for Professor Dippet. One gets the impression that he is a standard mid-level functionary, trying hard not to rock the boat, and rather worn out at the demands that being Headmaster of a school full of adolescent wizards and witches is putting on him. He quite possibly may resent having been left in charge to deal with the opening of the Chamber.

Questions

 * 1) To what extent did Armando Dippet understand Tom Riddle?
 * 2) How did Armando Dippet's Headmastership effect Dumbledore's development as a Headmaster?
 * 3) Did Dumbledore tell Professor Dippet how he felt about Tom Riddle? If not, why not? If he did, how much of Dumbledore's concern did Dippet accept? Why?