Jaggers is the criminal lawyer that Magwitch hires to carry out his plan to contribute to Pip’s “great expectations”. He is one of Dickens’ split characters. Although he defends convicts and crooks, he feels the need to constantly cleanse himself of the taint of this exposure to crime by washing his hands. While he can be harsh in representing his low-life clients, he has a soft side. He was the one who helped Miss Havisham adopt Estella because he “often saw children solemnly tried at a criminal bar, where they were held up to be seen....but here was one pretty little child out of the heap who could be saved." Jaggers represents Dickens’ view of the law, that probably needed much cleansing during the time period in which Dickens was writing, but he is also a sort of father figure to Pip. In the beginning, he was only helping Pip because he was being paid by Magwitch to help Pip become a gentlemen, but as the novel progresses, he develops a fatherly-like fondness for Pip.
John Wemmick is Mr. Jaggers' clerk and Pip's friend.He is also one of Dickens' split characters. He represents a person who has learned how to survive in both the public and private spheres of his divided existence. In the office, Wemmick treats Pip in a totally professional manner, but outside of the office, Wemmick is Pip’s friend, invites Pip to his house, introduces him to his father, etc. In this way, he is also a fatherly figure to Pip. Both Jaggers and Wemmick are people from whom Pip learns various lessons as he strives to accomplish his “great expectations.”
In Great Expectations Jaggers' character is significant in developing several thematic threads. Jaggers is significant in the theme of overbearing people who keep Pip feeling that he is in a fallen condition that requires constant repentance and moral cleansing. Jagger is one of the overbearing people Pip has to deal with, as Jaggers chew his finger and then throws it at Pip accusingly.
Jaggers is significant in the theme of guilt and corruption. Jaggers deals with underworld people and therefore lives in an environment of guilt and corruption, which he habitually attempts to wash from his hands with scented soap. Further, the central characters are all connected in guilt and corruption as the betray each other and are betrayed, for example, Miss Havisham's corruption of both Pip and Estelle.
Finally, Jaggers is also significant in the theme of destiny and its symbolic representation. Dickens' symbolizes the thematic element of destiny in this novel by chains. Jaggers represents and reinforces this theme by the presence of his watch chain. Pip acknowledges the mechanization of fate by alluding to a long chain that begins on one memorable day.
Wemmick is similarly significant in developing the theme of imprisonment. Pip always feels shut off from others everywhere he goes. Wemmick symbolizes this experience of being shut off because he only feels safe when he shuts himself up at Walworth.
[For more detail, read "Great Expectations: Imagery and Theme in Great Expectations."]