This is an interesting take on the character of Wickham in Pride and Prejudice. Wickham is seen as a villain for several different reasons in the novel, and they all relate back to the social system of England at that time. Wickham is first seen to be villain when we realize that he has told a very big lie about his past with Darcy. His version of the story is that Darcy is a liar who cheated him out of his inheritance from Darcy's father. He is telling this story to Elizabeth who already has a negative impression of Darcy as arrogant and elitist. This lie bolsters Elizabeth dislike of Darcy and holds her back from trying to understand him better. Wickham makes Elizabeth think poorly of the upper classes.
Another situation in which Wickham appears to be a villain is when he casts aside his interest in Elizabeth in favor of the more financially attractive Miss King who has recently come into a very nice inheritance. Wickham is a man without money who must marry for some. Elizabeth actually defends Wickham's actions to her aunt, but the whole situation leaves the reader with a less than happy opinion of the man.
When the romance with Miss King goes nowhere, then Wickham is just an attractive man on the loose whom Lydia thinks she is in love with. When he proposes the elopement, Lydia foolishly runs away with him. Elopements in Austen's time were not for marriage, but for sexual relationships without the benefit of marriage. This decision brings a huge potential scandal to the entire Bennet family. All of the sisters would suffer under the shadow of Lydia's immoral decision. This is why Darcy steps in to end the scandal. Darcy essentially bribes Wickham into making an honest woman of Lydia before the elopement becomes common knowledge. Wickham would have been no more interested in actually marrying Lydia than he was of marrying Elizabeth. Lydia has no money. But Darcy bribes him with the steady income of a promotion in the military and a VERY large sum of cash. The twenty thousand pounds he pays him would be equivalent to hundreds of thousands of dollars in modern money. Austen's audience would understand what an enormous sum of money Wickham received. Wickham manipulates Darcy into making this situation right. He plays off the social situation and expectations of society so that Darcy will step up and save the Bennet family reputation. He gets exactly what he wants in the end.