Mr Wickham is introduced about halfway through chapter 15 as 'a young man ... of the most gentlemanlike appearance'. He seems to be a 'completely charming' character. You can tell that Elizabeth really likes him, and you are prompted to like him too, as she is the principle character.
However it appears that Wickham has some kind of history with Mr Darcy as upon their seeing each other 'both changed colour, one looked white, the other red'. Neither Jane nor Elizabeth, the 'studier of character', could find any explanation for this exchange, so we are left wondering what this history could be.
Wickham soon clears this up in chapter 16, however, and we are given his account of why the previous meeting was so awkward. He told Elizabeth that Darcy's father had 'bequeathed' Wickham a position as a clergyman when he died, but for an inexplicable reason it was 'given elsewhere'.
Wickham says that Darcy's dislike of him was due to jealousy, as 'the late Mr Darcy' showed preference to his godson over his own son. It is noticeable that Wickham is very clever with his conversation, as he does not introduce the reason behind his and Darcy's mutual dislike until Elizabeth had told him that she did not like Darcy, and found him 'very disagreeable'. Having seen Elizabeth's character so far, I don't think that she would have believed Wickham's story so readily had she not had an already formed opinion of Darcy in her mind. Wickham's story confirmed her idea, and so she was more apt to believe anything else Wickham said as well.
Wickham caught 'the attention of every young lady' when he first appeared with Mr Denny, another officer. His good manners 'recommended him to everybody', and he appears to have a 'happy...