Charles is a man appearing in his mid-forties or fifties, with wrinkles lining the sides of his mouth from age. He has brown, short hair and eerily blue, cybernetic eyes that are capable of displaying in different visions as well as reading people's Demonic essence levels or Holy aura, read life signs and current health conditions, and other things. He most often wears a black tuxedo and is seen sitting in a spinning, floor-attached chair with a built-in glass holder and ash tray on the arm rests for his Scotch glasses and cigarettes. It is because of his attire and mannerisms that he is known as "the Gentleman."
Charles is often shown to be stern, serious, and pragmatic. He views the Hell-Hunters, his soldiers, even his own staff as mere objects. He holds the human will in high regard, and has made his own advancement his goal in life. He wishes to prove a mere Man can usurp God, though this is a secret mission. When around others, he states he wishes to protect humanity's interests and advancement.
For a majority of the series, he regards Sadow as a mere thorn in his side. However, during their final confrontation, he admits that Sadow has become an enemy worthy of standing against. He holds little value in the lives of others, disregarding the deaths of those around him. He displays a dispassionate uncaring when Sadow kills Dr. Greeves, citing that he knew of the man's betrayal but allowed him to carry on and continue his work in order to pose a threat to Sadow.
The only person he seems to actually care for is his own brother, Abraham, though even this is questionable. He allowed Abraham to take part in the Hell-Hunter program back when it was in it's initial, controvercial stage where it was first developing and those working on it were not sure of its success. He even pits his brother against Sadow, a clear threat, in hopes of eradicating him. When Sadow kills Abraham, Charles shows a clear sign of grief but quickly turns back into his former, dispassionate self.
He has no clear fear of Demons, staring at one through a glass wall without flinching despite its immediate hostility to the sight of him. He believes humanity is entirely in the will of the person, and that no matter what has happened to a person's physical being, so long as their will is intact, so are they. In this, he justifies experimenting on himself and transforming himself into a cybernetic-Demonic monstrosity.