Perhaps courtesy is not the right word, I will leave it for you all to determine...

I have always been struck by Darcy's courteous final words when leaving the parsonage, "Forgive me for having taken up so much of your time, and accept my best wishes for your health and happiness." Perhaps he's just trying to save face and leave with what little dignity he could muster, but then again he tells us disguise of every sort is his abhorrence. I think that with Darcy, what you see is what you get, as the old saying goes.

He also ends his letter in kindness "I will only add, God bless you."

When he talks of that wretched snake GW, he calls him Mr. Wickham unlike Caroline Bingley who shows her disdain by calling him George Wickham in her diatribe against him at the Netherfield Ball. As I understand it, that was quite rude and showed her contempt of him as beneath her just like she is overfamiliar in calling Elizabeth Miss Eliza.