Quote 1
"But Bonnie's the only one who believes me about Cuddledown," he says. "And I wanted to call you. Only not if you're a drug addict because drug addicts don't know what's going on." (22.20)
It's not because she's an addict that Cadence doesn't know what's going on. Nope, her brain is clouded enough all on its own without assistance from the pharmaceuticals.
Quote 2
"I have a boyfriend named Drake Loggerhead," says Mirren. "He's going to Pomona like I am. We have had sexual intercourse quite a number of times, but always with protection. He brings me yellow roses every week and has nice muscles." (25.40)
Mirren's imaginary boyfriend is straight out of a Harlequin romance. In case you've never read one, they're the books with the windswept guys on the covers who look like their names would be Drake Loggerhead.
Quote 3
"You have the only beachfront house, Bess, and you have all Dad's approval and devotion. I'd think that would be enough for you. Lord knows it's impossible for the rest of us to get." (66.26)
Bess actually doesn't have her father's devotion—none of them do, since he's devoted only to himself. But Bess has the most stuff, and to the other Sinclair sisters, that equals the most love.
Quote 4
"Carrie gets the pearls, Bess gets the Boston house, Bess gets Windemere…I'll be left alone with nothing, nothing, even though Cady's supposed to be the one. The first, you always said." (69.3)
Penny gets downright pathetic as the book goes on. Her degree of pathetic-ness is directly proportionate to her degree of drunkenness.
Quote 5
"[…] make sure Granddad knows. Tell him it's nothing and tell him it never was anything. Tell him he shouldn't worry about that boy again and then talk to him about Harvard and tennis team and the future you have in front of you." (67.29)
Even if Penny doesn't share Harris's racism, she wants to share his money, and that greed makes her betray her own child.
Quote 6
"Cuddledown is haunted," says Taft. "Can I come and sleep with you at Windemere?" (22.22)
Note that the Sinclair kids don't say my house and your house, instead calling the houses by name. It's kind of like the houses own them instead of the other way around.
Quote 7
"Granddad did nothing but fuel them […] Granddad was drunk on his own power and my mother wanted me to make a play for the money." (59.25)
All the aunts ask their eldest children to curry Harris's favor. They don't seem to be putting the littles up to it, though, just the Liars.
Quote 8
"Bonnie's obsessed with dead things. She's reading books about them all the time and then she can't sleep. It's annoying when you share a room." (24.26)
Here's another minor plot point that becomes extra-creepy when you know what happened: Bonnie's obsession with death is a way of dealing with the loss of her sister, Mirren.
Quote 9
"You could die. You could get hurt. If you are terrified, there's probably a good reason. You should trust your impulses." (28.47)
Trusting their impulses is what led to the Liars' deaths, so it's odd that Mirren('s ghost) would say this.