Lots of chapter titles throughout The Devil's Due series come from famous pieces of literature. You'll find quotes from Shakespeare, Christopher Marlowe (after whom our hero is named!), Rumi, Christina Rosetti, Dante Alighieri, Lewis Carrol, Lu Tong, Walt Whitman, Yeats, lots of Emily Dickinson, and many more.
There's even a line from our vulgar, messy, wet Renaissance writer, Rebalais!
There are also some film and music references heading several chapters and throughout all four books. Each of these references was carefully chosen to portray a mood or offer foreshadowing.
Here are some examples:
Chapter 1 of Deals with the Devil is titled with a line from WB Yeats' poem "The Second Coming." The poem is about the apocalypse, and the first line, which I used as the chapter title, evokes a sense of futility and anxiety. Yeats is used quite often throughout Book 1, including the title of the last chapter, "My Hour Come Round at Last", which is from the same poem. You'll also find his work heading several other chapters, particularly if there are Fae involved.
Chapter 2 of Deals with the Devil is titled "Sweet Honey", and it references "The Song of Solomon (4:11): "Your lips, my bride, drip honey; Honey and milk are under your tongue, and the fragrance of your garments is like the fragrance of Lebanon". Of course, there are many mentions of honey in the Bible ("with honey from the rock I would satisfy you", Psalm 81; "I have come to deliver them...and to bring them up...to a land flowing with milk and honey", Exodus 3:8), and most of them depict honey as sweet, fulfilling, a gift. But not all of them -- Proverbs 25 warns us not to eat too much, lest we vomit. John the Baptist in the New Testament ate only locusts and honey, and oh, those locusts will bedevil Luna.
In Devil's in the Details, we see chapter titles from John Milton's great epic Paradise Lost, the famous poem describing Satan's fall from grace. Devil's in the Details also gives us chapter titles from Aleister Crowley, the famous English occultist who is still revered by many of Satan's followers. He was also a painter and poet. In Devil's in the Details that chapters 10 and 17 are headed by his poem "Dionysus".
Book 3, Speak of the Devil, offers a chapter title from Lewis Carrol's Alice's Adventures in Wonderland: "If you want to get somewhere else, you must run at least twice as fast". This literally describes limbo. I turned to Carrol for inspiration in Book 3 because I wanted the Hells to be a place of chaos and absurdity, but I also wanted them to have a dark undertone, as Alice's adventures do.
A lot of bad things happen in the Hells, after all.
And finally, Book 4 brings us more of Milton's story of the Fall and Yeats' description of the end through several chapter titles and pieces of dialogue. But the great American poet Emily Dickinson reminds us in the very last piece of our story to have hope, even as our world burns around us.
Most readers don't remember chapter titles, and that's fine (I'm the same way). But I think they can, nonetheless, set a tone, build suspense and foreshadowing, evoke an emotion, and even just lend some added interest. One of my favorite authors, Seanan McGuire, often heads her chapters with quotes from Shakespeare, and although I don't always remember the quote itself, I always feel like they set the mood of court life among the Fae she writes about in her October Daye series.