|Previous Occupation||Prefect of the Green Lion house of Weston College|
|Manga Debut||Volume 7, Chapter 32|
Diedrich has short black hair, with his forelocks parted from the left. He dresses professionally, in a German military suit with black boots.
Vincent Phantomhive had described him as impatient. Intolerant and testy, he can be very rude, as he had immediately left right after Baron Kelvin attempted a conversation with Vincent; albeit, this can also be interpreted as him being secretive and cautious, particularly around outsiders.
As a former prefect of Green Lion in Weston College, Diedrich strictly adheres to the rules and will not hesitate to confront those who oppose it. He can become irritated with people who are tardy and irresponsible. However, Diedrich is capable of admitting and accepting defeat in a fair game, even to the person he is exasperated with; as he possesses great integrity, he intends to keep the promises he makes.
HistoryEditAs a young man, Diedrich attended Weston College and was the prefect of Green Lion, with Alexis Leon Midford as his Fag. He strongly disliked Sapphire Owl's prefect, Vincent Phantomhive, for his relaxed and unseemly behavior. After Vincent left all of the work for the school's annual cricket tournament to him, he confronted Vincent. The two decided to have a wager based on the results of the tournament, the terms being that the loser will grant one wish of the winner. Vincent won, and his request was for Diedrich to become his fag, with no time limit; this established their life-long affiliation.
Sometime later, Vincent called Diedrich back from Germany. He said that since he had helped Diedrich in the Windsor case a couple of years ago, he wanted Diedrich's help in his latest case. But before Vincent could tell him the details, Baron Kelvin interrupted them. Diedrich expressed disapproval of Baron Kelvin, opting to go to another room. He and Vincent then went to talk in private.
Phantomhive Manor Murder Case ArcEdit
Witch Forest ArcEdit
As Chlaus has later reported to Ciel Phantomhive, Chlaus visited Diedrich in Germany to ask for information about an unwonted disease and its questionable connection to the Witch Forest. However, Diedrich, as Chlaus has explained, coldly dismissed him, saying that he was busy.
Soon after, Diedrich receives a letter from Ciel that details of his expected arrival. While reaching for a sandwich, he comments to himself that Ciel brings nothing but trouble just like his father and that Ciel should look more like his father, now that he is thirteen.
- (To Vincent Phantomhive) "The leader is representative of the pack. It means that the people who would obey you are no better than you."
- Diedrich appears in the short story written by Yana Toboso for the Kuroshitsuji Comic Anthology called "With Father!" 
- Diedrich is nicknamed "Dee" by Vincent Phantomhive. On the other hand, Diedrich used to pejoratively call him "Mole."
|Agni · Baron Burnett · Aleister Chamber · Diedrich · Angelina Dalles · Fat nobleman · Charles Grey · Baron Kelvin · Lau · Alexis Leon Midford · Edward Midford · Elizabeth Midford · Francis Midford · Ciel Phantomhive · Rachel Phantomhive · Vincent Phantomhive · Alois Trancy · Countess Trancy · Former Head Trancy · Undertaker|