Okay first of all I nor anyone else on this site in any way owns the Canon characters of Kuroshitsuji, that being said there are few rules when using a canon character that must be used.
I do not like massive amounts of Occness out of characters. Sebastian for example would not suddenly go all lovely dovey gooey at the the sight of a dog. Even if Ceil was to order him to he would do only what he absolutely had to all the while calling Ceil a brat along the way. With that in mind the only place a Canon can go absolutely out of character is on the occ board. Which is where all out of context role plays and general comments go period. Anywhere else they will be deleted.