What are some textual evidences that explain Mr Darcy's character traits in Pride and Prejudice?
This is actually a complicated question. There is how he was initially reported to be. There is how he was initially perceived to be.
The gentlemen pronounced [Darcy] to be a fine figure of a man, ... and he was looked at with great admiration for about half the evening, till his manners gave a disgust ... for he was discovered to be proud; to be above his company, and above being pleased; and ... having a most forbidding, disagreeable countenance, and being unworthy to be compared with his friend.
There is how Elizabeth perceived him to be. There is how he perceived himself to be. There is how his housekeeper and his villagers perceived him to be. There is how he endeavored to prove himself to be.
He is expected to be wonderful because of his estate at Pemberley, because of his wealth and because he was so handsome. He was found to be horrible and proud because he wouldn't talk to anyone but his friends and he wouldn't dance (at a ball!). Elizabeth perceives him to be laughably haughty and proud because he couldn't be tempted to dance with her.
[Darcy] looked for a moment at Elizabeth, till catching her eye, he withdrew his own and coldly said: "She is tolerable, but not handsome enough to tempt me; I am in no humour at present to give consequence to young ladies who are slighted by other men."
He believed of himself that his upright, generous and reasonable actions would correctly bespeak his character to any who met him and that he would always be judged to be a worthy gentleman of admirable rank. His housekeeper says of him that he is beloved and well spoken of by all in his village (i.e., under his patronage) and that she herself had never had a cross word from him and that his sister Georgianna is devoted to him. After meeting Elizabeth at Pemberley, as he later tells her, he wanted to be perceived as truly changed by her words to him and to appear to be the gentleman he intended to be.
"I have been a selfish being all my life, in practice, though not in principle. As a child I was taught what was right, but I was not taught to correct my temper. I was given good principles, but left to follow them in pride and conceit. ... My object then," replied Darcy, "was to show you, by every civility in my power, that I was not so mean as to resent the past; and I hoped to obtain your forgiveness, to lessen your ill opinion, by letting you see that your reproofs had been attended to."