"What a beautiful day to go to Hell."
Sharon is leading Emma, Jacob and Addison into Devil's Acre. The sole name of the place foreshadows what they will find. Sharon has a cloak over his head and they are going by boat so it almost looks like he is the Hell's gate keeper and is leading them to the underworld. When they arrive the trio will literally find there what could be a representation of peculiar hell.
"“There’s more evil in peculiardom than merely your hated wights,” Sharon said, his voice echoing through the stone tunnel. “An opportunist disguised as a friend can be every bit as dangerous as an outright enemy.”"
Sharon is talking to Emma. Emma is a strong believer that all corrupted peculiars are trialled and put under a lock, but things aren't as simple as that, which the peculiar heroes will later find out in Devil's Acre. The second sentence foreshadows what will later happen with Bentham and how he will betray them. Not even Sharon was aware of his hypocrisy so maybe he should have listened to his own advice as well.
"But not just any hollow. My hollow. The word popped into my head without warning or precedent. Mine. Or maybe I had it backward. Maybe I belonged to it."
Jacob is already getting used to his connection to the hollow. It foreshadows the later events where he will grow compassionate with the monster. The connection comes naturally; Jacob is born with the ability so this quick adaptation is not surprising. Later in the novel he will literally be one with the hollows and be able to look through their eyes.
"If you make a habit of it, your ability
wears down to almost nothing—until you take more ambro. Pretty soon
you’re taking it not just to fight, but to function as a peculiar. You
become dependent on whoever’s selling it.”
Sharon talks about the clever way wights used Ambrose to control peculiars. Ambrose is made out of crushed peculiar souls so the peculiar who takes becomes a sort of cannibal. They didn't have to imprison the troubling peculiars because they became dependent on the substance and therefore dependent on the wights who sell it. It makes them wights' pawns that would do anything for just a drop of the drug.
