Recurring themes or patterns. As per the Repeat After Me by the Kongos, repetition is key.
>hole lore goes here.
>memory lore goes here.
>And here. Non-linear time lore goes here. And here.
>Deal lore goes here.*
*remember to read the fine print
oh god the ocean.
dude. how long do you have?
Games of Chance
Card games can be both parlor tricks and metaphors. They're versatile like that.
Poetry and Literature
Poetry and works of Literature make appearances throughout all the books in various iterations, both as simple world-building flavor (Dean memorizing passages of Shakespeare to impress a girl at one of his many high schools, for instance) and metaphor. The series title "Down to Agincourt" itself is taken from the last line of the Henry V fan-poem Harry Takes the Field by bratfarrar
The outcome’s known. Why try?
Return your rusty sword to battered sheath,
bow your head and bend your stubborn knee.
Why take the field when you cannot win the war?
But Harry—he went down to Agincourt.
"Didn't feel like going quietly into the good night, I take it?"— Lucifer Map of the World, Ch. 1
Lucifer says this to Cas after looking him over and finding him bloodied, but alive, when Cas returns for Dean's body in the opening scene of book 1. This line is an allusion to Dylan Thomas's poem, Do Not Go Gentle into That Good Night,
[A] fitting poem about refusing to surrender to death. It is all the more poignant that the quoted line should be followed in the poem by "Rage, rage, against the dying of the light" as Dean is often referred to as light, and this scene immediately follows his death.
"Thank you." As if they belonged to someone else entirely, he watches his own bloody fingers close the dulled green eyes that had once housed the last light left in all the world.— Map of the World, Ch.1
. . .Good men, the last wave by, crying how bright
Their frail deeds might have danced in a green bay,
Rage, rage against the dying of the light.
[. . .]
And you, my father, there on the sad height,
Curse, bless, me now with your fierce tears, I pray.
Do not go gentle into that good night.
Rage, rage against the dying of the light.— Dylan Thomas
"'For an angel is nothing more than a shark well governed'." Turning on the step, Castiel stares at him, and Dean's innocent expression cracks almost immediately. "I can also do the entire Mark Antony funeral speech from Julius Caesar."
"What was her name?"
"Victoria, junior year, fourth high school that year." Dean's grin widens. "Couldn't play football, we were moving too much, so had to work with what I had."— A conversation between Dean Winchester and Cas. Map of the World, Ch. 6
Dean makes several references to famous works of literature he read in high school, ostensibly to impress young women, but also simply because, as we later learn in Book 2, he simply enjoyed them. In addition to Moby Dick and Julius Caesar, Dean name-drops John Milton, of Paradise Lost fame, Dante (Inferno, The Divine Comedy), and William Blake; his retention of them all, he claims, is "fucking awesome." All of which, also notably, are thematically appropriate.
"You got a thousand miles to go before you sleep. Did I get that quote right?"— Amieyl. Map of the World, Ch. 11
During the fever dream brought on by the brownie bite infection, Dean meets Amieyl, who mis-quotes this line from Robert Frost's Stopping by Woods on a Snowy Evening. It makes a recurring appearance throughout the rest of the dream as an anchor for Dean to cling to when he needs reassurance to keep fighting in order to wake.
Fittingly, the line Amieyl intended to quote in the poem is proceeded by the following:
The woods are lovely, dark and deep,
But I've got promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.— Robert Frost
Both Dean and Cas make promises to each other in this chapter: Cas, to a delirious Dean who thinks he's speaking to the Godstiel of his timeline, and promises to return Sam to him; and Dean, who later promises not to die (and, to himself, not before getting to show Cas what makes life worth living).
Journey to the-- or, Hippo Porn
"What are you reading, anyway?" Dean asks immediately, craning his neck to decipher the illegible title. Resigning himself, he picks it up and passes it to Dean, who flips it open, squinting at the pages with a dubious expression before turning it sideways. "Okay, I give up, what is it?"
"Evidence suggests it's the greater part of a very bad epic poem by a disappointed Athenian student who was refused study in the Library of Alexandria," Castiel tells him.— A conversation between Dean Winchester and Cas. Map of the World, Ch. 6
The humble beginnings of the infamous Hippo Porn. "Journey to the—" (title unfinished) is a rudimentary work of epic poetry discovered amidst a collection of Bobby's books that makes frequent reappearances throughout the series. Vetted as a work of fiction and not a summoning ritual for the goddess Tawaret, it is currently in the process of translation from demotic Egyptian (courtesy of Cas) to appeal to a wider audience. Originally translated to share with Dean, the Hippo Porn has gained camp-wide notoriety after Vera was invited to listen in on readings during Dean's recovery.