1) Diederich have learned Vincent’s death by Klaus, come in Germany for say the horrible new to his friend’s best friend. Tanaka and Klaus have decided to not send a letter, because just a letter would have been too cruel. Specially in Tanaka’s mind since he knew the exact relation between the two man.
2) When he lave learned that Ciel was alive, he have immediately call him for know if he was alright and if he had need of help.
3) He regrets always to not be returned to England to search the child when Klaus told him that nobody had found the body of the child. 
4) Since Ciel’s return, he calls him all 2 or 3 months.
5) Ciel have never suspected the german guy. Because for him it’s impossible that he be the culprit.
6) Edward likes Ciel, really, but he likes his little sister more.
7) Ciel have actually decided that, when he will die (certainly before that he could be married and have one child), Phantomhive title belongs to Edward for that his cousin take care of his family affair. And it will be his second son or Elisabeth second son who will inherit to Phantomhive’s stuff!
8) If Ciel survives to the contract for some reason, he will name his two sons Matthew and Vincent. Matthew because have a child (or more that one), for him, is a God’s gift and because his second son should have his dear father’s name.
9) Diederich hated Baron Kelvin because he have acted like a fanboy with Vincent and have too often look at Ciel with a too marveled look. So when it has happened again, he have taken the little boy with the excuse “your mother want to see you!” Vincent, laugh and says “Dee, you are a overprotective godfather!”
10) When Vincent is dead, Diederich was going to have, with his wife, his third child. It was a boy. He called him Vincent!
11) Vincent was a sadistic person. With the criminals. But also with his friends, not the same type of sadism but still…
12) Sometimes he was too sure of himself, and be saved by his best friend.
13) Vincent liked to be the uke but still the real dominant in the relation!!
14) He stayed human,thank to his family, Tanaka, Klaus and Diederich
15) Nobody could say “No!” to vincent, Nobody! Except Rachel, Frances and Ciel.
16) Madam Red have actually seen the mark on Ciel’s side. She have given a hug to the boy.
17) Ciel likes “Sherlock Holmes”, and enjoys all Arthur’s new books.
18) Ciel speaks French very well but very poorly German.
19) Both Ciels are actually not two different Ciels. It’s the same with the feel of revenge, matureside, on a side and the innocence/child spirit at the other side. Normally they both work together but when Ciel is traumatized, his childish side takes advantage of the situation for acted like his age.
20) Ciel is sometimes a little jealous to Edward to have a normal life. But he try to keep his cousin away from business to the shadows to preserve his innocence and joy of life! Because the time where Edward must help him could arrived more early that late.
21) Diedrich is Ciel’s godfather.
22) Nobody ever knew really the exact relation between Vincent and Him.
23) Diedrich have do a depression after Vincent’s death.
24) The murderer of Vincent et Rachel were a “friend” of the family. It’s explains Takana’s surprise when his master is killed (chapter 19). He’ doesn’t attack, he’s petrified!
25) Undertacker want to protect Ciel from Sebastien!!
 Can you imagine how Black Butler have turned if Ciel have been saved by his uncle Dee?