Despite his "dark face, with stern features and a heavy brow", Jane finds in him an equal, and the traditional master-servant relationship breaks down between the two.
Although St John initially appears perfect, Jane soon detects a restlessness or hardness under his seemingly placid features; he is "no longer flesh, but marble" and his heart seems made of "stone or metal."
His reserve and brooding suggest a troubled nature, and his zealous Christianity offers him neither serenity nor solace. St John's feelings about Christianity are revealed in his sermons, which have a "strictly restrained zeal" that shows his bitterness and hardness.
Throughout the course of their conversations, Rochester tells Jane of his past, not only revealing his growing faith in Jane, but also showing the Byronic side of his nature. Like Lord Byron, a romantic, passionate and cynical poet of the early nineteenth century, Rochester lets himself be ruled by his "grande passion."
While Rochester vents his passions, St John represses his. The iciness of St John's character is most pronounced in his relationship with Rosamund Oliver. Although he "flushed" and "kindles" at the sight of her, St John would rather turn himself into "an automaton" than to succumb to Rosamund's beauty or fortune. His ambition cuts St John off from all deep human emotions.
Rochester, on the other hand, constantly reminds Jane, he is not "cool and dispassionate"; instead, he seems to devour her with his "flaming glance". St John is a person that shows no emotion in his face towards others, unlike his sisters or Rochester Jane is unable to sustain any intimacy with him. Even on hearing of the death of his uncle, he delivers the news to his sisters with an uncaring and detached manner. It is recognised that St John will crush all of his natural feelings in order to achieve his ambitions. Jane characterises this using metaphors of ice, marble and stone, to convey how strong her view of him is.
Rochester wishes to marry Jane as he finds in her true love and a soul mate. He plans to change his lifestyle and give up his wild and dissipated life on the continent in search for freshness and freedom he feels Jane can bring him. He is even willing to flout social conventions and disregard class boundaries in order to continue a warm and loving relationship with Jane.
St John, however, proposes to Jane, for the reason of his choosing to go to India as a missionary, and for Jane to accompany him as wife. For St John, it is obviously a marriage of convenience, desiring Jane in terms of labour, and not love. He wants someone he can "influence efficiently" and "retain absolutely," rather than someone he loves. Marriage to St John would traumatically erase Jane's identity and douse her passions for life.
St John appears to have no emotional feelings towards Jane, believing that passion should be turned into a calm and detached love for all mankind. This is due to his believing that religion shaped every aspect of a person. These are the same religions views which were instituted at Lowood, and as Jane disliked being in the presence of Brocklehurst, she is certainly not going to marry a replica of him.
The two men, Rochester and St John, are like ice and fire. While St John's blue eyes and ivory skin align him with ice, Rochester's dark hair and passionate nature connect him with fire. After St John proposes to Jane, her subconscious tells her the right thing to do - return to her true love, Rochester.
