Chlaus is a middle-aged man with blue eyes and blond hair drawn back in a tidy ponytail. He is inclined to wear exotic clothing; he prefers to dress in ornately-decorated ties and suits with particular patterns on them.
Chlaus is a vigorous, adventurous individual; he often travels, and has a habit of speaking words and phrases from countries he has recently been to. Furthermore, he is cordial, as he tends to enthusiastically express his gratitude for great service. He fancies a lighthearted, humorous atmosphere over a strict, businesslike environment.
At a ball, the young Ciel Phantomhive approached and happily hugged Chlaus. Vincent Phantomhive warmly greeted him as well, and Chlaus stated that it was a rare occasion to see them all together. Vincent commented that he was gone for a while; Chlaus, then, responded that "German beauties are made of tough, virtuous stuff," and Vincent offered to help relieve the tension the next time.
Black Butler Arc
Chlaus arrives at Phantomhive Manor and meets Ciel Phantomhive at the front steps. Chlaus greets him joyfully, and when Ciel responds to him in a blunt manner, he jokingly tells him that he is as rude as ever. The Phantomhive servants courteously welcome him, and Chlaus notes that the manor is beautiful along with the fact that Finnian is a relatively new addition to the household. Sebastian Michaelis leads him to the courtyard, and Chlaus remarks on its magnificence. He is seated at a long table, along with Ciel, and Sebastian prepares them tea.
Soon after, Ciel asks for the "usual goods," and Chlaus passes him the "game" that has been difficult to obtain as it has not yet been released in Italy. Chlaus questions if he is obliged to deliver the next one soon, and Ciel affirms it, saying that children have a greed for games.
Sebastian then serves the evening meal. Chlaus is initially inquisitive of the dish, but Sebastian stuns him with an overwhelming story on its background. Chlaus laughs heartily, stating that Ciel never ceases to surprise him, and praises Sebastian's vast knowledge. Because he is conversing, he fails to notice Mey-Rin accidentally spilling wine on the tablecloth. Sebastian swiftly removes it, and when Chlaus returns his attention to the table, he is shocked to see that the tablecloth is missing. Ciel tells him to disregard it, and eat at his own leisure.
Afterward, Chlaus comments on Sebastian's extraordinary talent, and much to his amusement, Ciel reveals that one of the reasons he hired Sebastian is for his delicious sweets. Subsequently, Sebastian brings out the after-dinner dessert.
Later at a meeting between the noblemen, Ciel reveals that he has received the ingredients from Chlaus; they are actually drugs, and Chlaus has strenuously obtained them as evidence of the Italian mafia's crimes, that is to be presented to the government.
Emerald Witch Arc
While Chlaus is enjoying a sauna in Finland, Sebastian Michaelis suddenly appears, much to Chlaus' shock. He relays to Chlaus that Ciel Phantomhive wants him to visit Diedrich in Germany in order to investigate the mysterious deaths there. Later, Chlaus goes to report to Ciel personally over dinner. He states that he had gone directly to Diedrich upon arrival in Germany, but the latter just "coldly brushed [him] off"; therefore, Chlaus went to the village and mansion where the abnormal deaths occurred himself—he says it was a difficult trip, as they were so far in the countryside. He relates that there are no wounds or chronic or contagious disease around there; however, all the inhabitants there have claimed that the deaths are brought about by the "witch's curse." Chlaus proceeds, asserting that all victims have one thing in common: they have all visited the Werewolves' Forest before they died.
Ciel believes that the so-called curse is an absurd thing, and Chlaus laughs and gives his apology for his inability to gain more information on the matter. Ciel assures him that he will do further research, and moves on to inform of Undertaker's disappearance. Chlaus says that they never interfered with each other much and that Vincent Phantomhive knew Undertaker first. He adds that the only one who knew Vincent before Undertaker was Diedrich. Ciel and Sebastian decide to visit Diedrich since they are heading to Germany anyway, and Chlaus jocosely cautions Ciel to be careful, as Diedrich is not a friendly sort of man.
- (To Ciel Phantomhive) "Here is the game you wanted. It wasn't released yet in Italy. It was difficult to obtain."
- "My, my, if it's a game and such that 'kids' can handle, then it will be effortless."
- (To Ciel Phantomhive, about Diedrich) "German beauties . . . I mean, former beauties, are quite stiff. You'll have to play him well, junior."
Out of Universe
- According to the official Kuroshitsuji character popularity poll, Chlaus is the fifty-fifth most popular character in the series, with two votes. He shares this spot with Funtom Corporation's rabbit, Arthur Randall, Ludger, Alan Humphries, and the Prince Albert puppet, who also received two votes.