How could we compare or contrast the characters of Mr Darcy and Mr Wickham?
Thematically speaking, the characters of Mr. Darcy and Mr. Wickham digress in just about every aspect of the novel. This is because, even though they come from different backgrounds, they did have a similar upbringing which Darcy's father's death would lead to their definite separation.
When it comes to the theme of "pride", the two men can certainly be considered proud, but differently. While Darcy's pride comes out of the legacy of his family name and history, Wickham's comes from greed, arrogance, and from his determination to feed his ego by ruining good women.
As far as marriage goes, Darcy certainly maintains the customs of the upper classes to marry their own kind, until he meets Elizabeth and then everything changes. Contrastingly, Wickham is an immoral (or amoral) libertine who prefers to elope with young women to ruin their reputation, or else to marry uniquely for money.
In terms of behavior, we know already that Darcy's inability to be sociable comes from his lack of experience with "the masses". He is, after all, a gentleman of high birth and is used to a specific "set" of people. Perhaps the Bennets are his first (and most unfortunate) brush with a "peasant" family of good means, but no title. Granted, Bingley's fortune was not acquired through the most honorable means, but he still belongs to the "London set" that would make him "fashionable". However, we learn upon Elizabeth's visit to Pemberley that Darcy is actually a kind and decent man who is humble and tender, even to his servants. His behavior is deceiving, but for the better.
Wickham ends up in the military as a last resort since his squandered away the money that Darcy's father (who is also Wickham's loving godfather while he is alive) allotted him upon his death. However, military discipline does little to curb Wickham's natural ability to deceive for the worst: he uses charm, a sad (invented) story about himself, and his attractive looks to cause harm, and to lie to others. This is how Elizabeth falls for him, and then realizes bitterly how wrong she had been once he betrays her family by running away with Lydia.
Overall, Darcy and Wickham are two young men that come from respectable families. Darcy comes from high breeding while Wickham is the son of a respectable man who managed Darcy's father's estates. This closeness allowed Wickham to have a good upbringing along with Darcy, even gaining the love of Darcy's father. However, the nature of their characters separate them greatly, as well as Wickham's greed and talent to deceive. If it had not been for those aspects, Darcy and Wickham may have been easier to compare than to contrast.