I edited your question because you can only ask about one character per question on Enotes. I hope this helps:
Darcy's character was very proud at the start of the story in that he held high esteem in his own and his friend's position in society, the things that they, as upperclassmen had earned either virtuously or not, and in the pride of coming from good lineage.
He was prejudiced in that his pride made him look down on others, even Elizabeth, and made him set himself and his equals aside from the country people and their customs.
Darcy's transformation is actually comical, and it is said that Austen made his sudden mad and crazy love for Elizabeth a sarcastic underline joke.
He had no real reason to change. He even put down Elizabeth during his proposal and reminded her of her lower status and how great she would do if she married him! Yet, after this incidence, and after Elizabeth's refusal we could assume that Darcy got a huge reality check from a source which he actually respected, which was Elizabeth, her wit, and her charisma.
Hence, we could safely assume that Darcy changed as a result of what Elizabeth declared in her refusal, and because of the refusal itself: He basically got shaken off his high horse by someone whom he considered his "subject", and he was told what he needed to hear.
Now remember, Darcy was never a mean man with his own people, nor with his servants. Everyone had a good word to say on his behalf. We can conclude on this that Darcy was prejudiced only against people he did not acquaint with regularly.
We can say that Darcy will never stop being proud. To him, pride is a good thing, what is bad is hedonism, or petulance, and he stopped that practice with Elizabeth. Therefore, love may have been the agent of change in Darcy in terms of his prejudice. Has he given pride and prejudice altogether? We can hardly think so, but he did get much better at communicating and being a better person to others.
first understand that social conventions in England during the 19th century held manners in the highest regard as well as the class structure. We are only concerned with two class structures the aristocracy and the landed gentry the only difference between them was money. Every story that Jane Austen wrote - a reference to $ is found with-in the fist lines of the first paragraph.
Darcy in a way was isolated from the landed gentry as he grew-up at Pemberly in the Devonshire country side. He even admits that his ability to converse with those he is not familiar with is lacking.
He has fallen in love with Elizabeth who is in a different class than he, the landed gentry and has nothing to bring to her marriage, only herself.
The turning point of the novel is when Darcy proposes to Elizabeth and she rejects him on the grounds that he insulted her by defining her position within the class structure of the landed gentry - separating her sister from his best friend because of the propriety of her family. Basically he was lowering himself to her level on her behalf, which Elizabeth did not appreciate and enlightened Darcy on his own short comings that she presumed that he had. What you need to know is that these social convention were manners that were ingrained and that when Darcy proposed to Elizabeth he was only following the social conventions of his class and not trying to insult her... why would he if he wanted her hand in marriage. So, after he wrote her the letter in which he intended to make amends to her reasons for rejecting him the plot of the story begins to fall and eventually they meet at the same level - thus overcomes these follies you are stuck-on. Mark