It's her guilt that she wants to be torn to bits, devoured, to disappear. Bradwell. She thinks of him now […] (1.21)
Probably one of the most guilty-feeling people in this book is Pressia because she saved Bradwell's life by injecting him with a serum. Guilt follows her around everywhere, making not only her mission harder, but also her love for Bradwell.
El Capitan slides down and sits there, feeling a pang of guilt for shoving his brother so hard. He hates the guilt. (3.45)
El Capitan is racked with guilt—not only for what he used to do in the OSR, but by the way he continues to treat his brother.
"We can own up to them now. And we can feel the guilt at last. If we do, that's how we can maybe—just maybe—be forgiven." (4.83)
Partridge uses these lines in part of his speech to the people inside the Dome. Unfortunately, this guilt is too much for the Pures, leading them to commit suicide.
They've held on to a lot of guilt and anger and blame for a long time.(6.66)
This goes along with the theme of lying; the effect of an extended lie is extended guilt. This extended guilt eats away at the Pures, reducing them down into—you guessed it—guilty liars.
El Capitan know the signs of festering guilt—intimately, from the inside out. (8.60)
Well, he's the guy who used to kill people for fun. So yeah, guilt is just second nature for El Capitan.
"The people in the Dome have survivors' guilt. They hate all who survived on the outside because they hate themselves." (8.106)
Survivors' guilt is a term we use for people who feel guilty (and undeserving) for being alive. The people inside the Dome all have this, because they were the ones who were saved from the Detonations.
Sin is sin—individual and collective. His life is full of it. (8.76)
Again, the more you sin (individually or as a group), the more guilt builds up. And the more the guilt adds up, the more likely you are to having a breakdown.
The guilt washes over him. It's his fault. He's to blame. He squeezes Lyda's hand and she squeezes it back. At least he's not alone. (10.3)
Without Lyda, Partridge's guilt probably would have driven him to suicide as well. Sometimes all you need is a little support to get past feelings of guilt.
"As long as the wretches wear our shared history on their skin, there will be no peace. Guilt, Partridge. You can't live with all of that guilt without wanting to blame the victims and exonerate yourself. Human nature." (14.119)
Arvin Weed is right on the money with this quote; when you feel guilty, it's easy to start playing the blame game so that you can pass your guilt along to someone else. It's "human nature," as Weed explains.
Partridge is going to walk down the aisle cowed by guilt. He tried to lead and it was all stripped away. (14.33)
Partridge's marriage to Iralene is part of a huge lie — by telling the Dome the truth in the beginning of the book, Partridge rid himself of guilt. But then he built it up again by lying more. This is where guilt and lying go hand-in-hand.