How we cite our quotes:
"I'm not afraid in this way [of the sea]," said little Em'ly. "But I wake when it blows, and tremble to think of Uncle Dan and Ham and believe I hear 'em crying out for help. That's why I should like so much to be a lady." (3.72)
When Emily is rushing towards the sea, David admires her courage. But Emily isn't afraid of the sea for herself. She's worried about what the sea has done and will do to her family. Emily's father and uncle (Ham's father) were drowned, and this childhood trauma has strongly affected her development as a character. It's because of her sorrow at the loss of her family that Emily is so desperate to become a lady. She wants to have the money to protect Mr. Peggotty and Ham from their dangerous profession, fishing. And it's because Emily so wants to be a lady that she becomes vulnerable to Steerforth's seduction.
"It's enough to distract me," cried my mother. "In my honeymoon, too, when my most inveterate enemy might relent, one would think, and not envy me a little peace of mind and happiness. Davy, you naughty boy! Peggotty, you savage creature! Oh, dear me!" cried my mother, turning from one of us to the other, in her pettish wilful manner, "what a troublesome world this is, when one has the most right to expect it to be as agreeable as possible!" (4.10)
When David comes home to find Mrs. Copperfield married to Mr. Murdstone, he's not exactly overcome with joy. And in her disappointment at David's reaction, Mrs. Copperfield strikes out at David and Peggotty for being "naughty" and "savage" at not being happy for her. Mrs. Copperfield can't understand why there is still suffering in a world when "one has the most right to expect it to be as agreeable as possible." The thing is, why do we have a right to expect the world to be nice? Not to sound like our crotchety grandparents or anything, but who says life is fair? Maybe Mrs. Copperfield's assumption that she's owed a good life makes her all the more disappointed and unhappy when she suffers.
I should think there never can have been a man who enjoyed his profession more than Mr. Creakle did. He had a delight in cutting at the boys, which was like the satisfaction of a craving appetite. I am confident that he couldn't resist a chubby boy, especially; that there was a fascination in such a subject, which made him restless in his mind, until he had scored and marked him for the day. I was chubby myself, and ought to know. (7.7)
Mr. Creakle is obviously a sadist. He "had a delight in cutting at the boys." He loves whipping boys so much that he feels "restless in his mind" until he finds a new victim. But it's also worth noting that David remembers Mr. Creakle so vividly and fiercely because of the suffering he brings – the reason there's so much pain and sorrow in this book is because it's these things that we remember. And David Copperfield is supposed to be a memoir.