Stevenson introduces and explores ideas about the dual nature of man by using the characters such as Utterson, Jekyll and Enfield as constructs to symbolise hypocrisy and explore themes about good and evil and how themes such as science pose as a threat to the Victorian's main belief of Christianity, which explains their intense fear for any scientific related theories.
At the beginning of the novella, Enfield describes Hyde's overall appearance as a "damned juggernaut" which emphasises Hyde's inherent evil and unstoppable nature. By using "juggernaut" which links to the Hindu God Jagannath, there is an immediate threat against Christianity, by mentioning a being which would have been viewed as barbaric in the eyes of the Christian reader. However, Enfield gives an additional detail about the girl that Hyde trampled, indicating that the "child was not much the worse" which could begin to develop the theme of the ambiguity of Hyde's evil, possibly hinting towards the idea that these initial impressions of Hyde may be over the top and based on an inherent prejudice, rather than any actual harm caused. Stevenson may have chosen to do this at the start of the novella in order to create a strong, shocking introduction to Hyde which aligns with the Christian viewpoints and perspectives on the idea of evil. However, at the same time, he could be subtly causing more perceptive readers to feel doubt and to question whether this melodramatic source is reliable. This is further conveyed when Enfield casually states that he and the Sawbones "screwed him up to a hundred pounds". This further introduces the theme of hypocrisy within Victorian society. Two respectable figures immediately resort to blackmail and become hostile towards Hyde, who in this moment, has only trampled a girl. This portrays a sinister undercurrent underneath their pristine appearances. Stevenson could be trying to criticise the moral standards that Victorian society has, revealing their capacity for cruelty and prompting readers to think who should true "damnable" person is.
Later on, Utterson states that he claimed to have "read Satan's signature" on the face of Hyde. This is Stevenson highlighting to the Christian audience that Hyde is the embodiment of pure evil. However, astute readers will realise that Utterson is simply accepting a preconceived statement due to it being regarded highly by his high - class peers. A person's face cannot determine their behaviour or moral compass. Stevenson is highlighting society's fears of something unchristian and also attacks their fears of Darwinism, indicated that man's true nature is to evolve to become fitter rather than for moral improvements.
Stevenson introduces Jekyll, who has already been stated to have been "wrong in the mind" (by Lanyon) due to his scientific experiments being viewed as abhorrent. Jekyll is confident that he can "be rid of Mr Hyde" inviting us to understand that he is deceiving himself and is trapped in self delusion. Stevenson could be conveying the idea that a person's duality doesn't only stem from good and evil, it also stems from their conscious and whether or not they are self deceiving or aware of their true natures. Jekyll knows that his association with Hyde is "sinful", but also wishes to remain delusional to his realisation as he enjoys the pleasures Hyde gives him. He urges Utterson to do the same, as he knows that Utterson also will experience the duality of delusion and conscious.
Stevenson then shifts the focus onto the murder of sir Danvers Carew, the murder confirms the evil of Hyde, due to him "clubbing him (Carew) to the Earth" with "ape - like fury". This is another introduction to the dual nature of man, which lives underneath the façade of a proper gentleman with decorum. The audible imagery of "the bones were audibly shattered" further amplifies the extreme horror and vicious act. However, an alternative interpretation to this could be that the description appears to be quite hyperbolic which may indicate that this description may not be the most reliable source. This hyperbole could have been used by Stevenson to mock Victorian readers of their dual natures and how hard they try to conceal it. They claim to be respectable individuals yet at the same time, have an intense fascination with crime. By using duality as the main focus for the overall story and the characters, Stevenson wants the reader to think about whether the Christianity of what is sinful is correct. This would be fitting as Stevenson is an atheist who opposed Christianity.
Stevenson deliberately allows Utterson to question Jekyll and suspect his association with Hyde. However, despite being a lawyer, a position which would have been highly respected at the time, Utterson deliberately chooses to disregard all signs of Jekyll's association with any of Hyde's crimes. When guest announces that "Henry Jekyll forged for a murderer", Utterson makes guest keep swear to remain silent and to keep a secret. Utterson also "locked the note into his safe", despite having the power of putting Jekyll into trouble, which would have been the most 'Christian' thing to do, he chooses to hide Jekyll's crime and Stevenson could be indicating that the duality of good and evil not only exists in people, but in social structures and social hierarchy.
Stevenson even uses setting to indicate the spread of duality and hypocrisy across all of London, referring to it as a "great chocolate covered pall". "Pall" indicates that London has "killed" Heaven and has removed all traces of it due to their hypocrisy, a pall represents a shroud which is placed on top of a corpse. This juxtaposes to the pleasant "chocolate" and by comparing a "pall" to "chocolate", Stevenson is undermining that the sins and the duality of the Londoners has a powerful attraction and is able to overwhelm everything around them.
Towards the end of the novella, Jekyll begins to describe how his creation could have been an "angel" instead of a "fiend" had he kept his intentions moral. This is another link to the duality of good and evil and uses the Biblical imagery of "angel" in order to appeal to the Victorian readers. Stevenson may have chosen to do this because he wants to make the message clear that all humans have duality within them, however, it is up to us to decide what we do with it. The beholder of this dual nature should accept both sides rather than repress them as they cannot contain them both, however, they should not allow evil to cloud their minds.
In conclusion, Stevenson presents the characters in this play as unreliable and stresses the idea of not disregarding dual nature or concealing it as it is a part of human nature that cannot be removed. Jekyll makes this realisation in the end, when he accepts that "man is not truly one, but truly two" portraying it as the "primitive duality of man". This highlights that concealing one's desires will cause more destruction due to the evil within becoming even more desperate to be unleashed and will "come out roaring".