He is a demon and he has a line similar to that of Sebastian’s, which is “私は旦那様を飽くまで貪りたい” (Watashi wa danna-sama wo akumade musaboritai) which means “I want to greedily devour you to the end, my master.” The kanji of “akumade” might mean something else.
Claude has a different personality than that of Sebastian Michaelis in which he speaks and acts motionlessly, not even responding to direct taunts from Alois, such as him undoing his buttons moments after Claude fixed them. He seems to know Sebastian well, but within moments of seeing each other they begin to fight.
He is very loyal to his master and knows his master’s darkness.
He has black, short hair and wears glasses similar to those worn by William T. Spears. He has yellow, slanted eyes and a somewhat angular facial structure. His chin is quite flat. Claude can transform his body like Sebastian.
Like Sebastian, his contract mark with Alois is one his left hand covered by the gloves he wears. However, his mark isn’t always visible, only becoming so when he nears Alois.
Claude says “Yes, your Highness” when following Alois’ commands, whereas Sebastian says “Yes, my Lord.”
This is probably due to the fact that Claude seems to hate Sebastian.
In the first episode he is seen in the form of a spider before making the contract with Alois.
In episode 4, it is shown that his tongue is incredibly long, reaching to the upper of his nose at rate.