Game of Thrones delivers secrets paid with the blood of beloved characters. Hold the door, indeed.

In a season of death and resurrection, the sixth installment of HBO’s franchise has finally addressed the cold history of the White Walkers. Though “Winter is Coming” remains the show’s most remembered tagline, few people outside the brain trust of George R. R. Martin know when, why, and how the overseers from the Land of Always Winter will cast their spell over Westeros. As season six reaches the halfway marker, we take a moment to shed some light on the darkest forces in A Song of Ice and Fire.

Here are the 10 Things You Need to Know About White Walkers, but be warned, SPOILERS lie ahead for season 6 of Game of Thrones.

10. First Attack: The Long Night

White Walker Approaches Sam and Meera Game of Thrones: 10 Things You Need To Know About White Walkers

Do White Walkers bring winter, or do they simply take advantage of it? The answer to this elemental question holds huge ramifications, beginning nearly eight thousand years prior to the Targaryen Conquest (which itself took place about 300 years before the events of the book/TV series). During the generational pall of The Long Night, which saw a lifetime of cold and darkness descend on Westeros, the White Walkers first emerged. As Old Nan tells a crippled Bran, the humanoid creatures “swept through cities and kingdoms, riding their dead horses, hunting with their packs of pale spiders big as hounds.”

While Nan’s tale remains hearsay throughout the land, recent events confirm the growing hordes of White Walkers and their army of the undead. History will indeed repeat itself, and you can expect gigantic ice spiders will be there when it does.

9. The Night’s King

The Night King in Hardhome e1464149630260 Game of Thrones: 10 Things You Need To Know About White Walkers

Colloquially known as “the horned one,” the Night’s King is the designated leader of the White Walkers. The most menacing of his comrades, the Night’s King is the “Adam” of his race, the originator of the White Walkers. A victim of Leaf’s heart-bound dragonglass dagger (more on that later), the former member of the First Men became the first White Walker in existence.

While divergences between ASoIaF and Game of Thrones are clear, the literary roots of the Night’s King (played by Richard Brake, best known as Joe Chill from Batman Begins) are worth exploring. As George R. R. Martin tells it, the Night’s King was a champion of the battlefield and the thirteenth Lord Commander of the Night’s Watch. His military career dissolved, however, after following the desires of his heart. These passions took him beyond the wall and into the arms of…

8. The Night’s Queen

Night King and the Baby Game of Thrones: 10 Things You Need To Know About White Walkers

While Craster’s sons appear to be a primary source of reproduction for White Walkers, rumors of their mating with wilding women abound. The roots of the Night’s Watch celibacy pledge may actually find its history in the Night’s King, whose heart was ravished by a female White Walker. Though she had “skin as white as the moon and eyes like blue stars,” the Lord Commander took her as his wife, and in turn, gave her his soul.

As the Night’s Queen, she reigned with him at Nightfort and turned their bastion of defense into a destination of wantonness and extreme violence. As Craster did throughout much of the show, The Night’s King made sacrifices to the White Walkers until he and his queen were finally deposed by Brandon the Breaker. Ever after, the Night’s King’s name was stricken from the history books, inspiring speculation that…

7. The Night’s King May Be A Stark

Bran Stark with the Raven Game of Thrones: 10 Things You Need To Know About White Walkers

Temporarily suspend Bran’s time-traveling implications and his curious ancestry of Brandon the Breaker and Brandon the Builder. Now, ask a simple question: why don’t we know the Night’s King’s name? The records of his rule were destroyed and all memory of his existence wiped from history. Why? Quite likely to preserve the honor of a House. In a world where titles are everything, the Night’s King is nameless (or, to borrow from Martin’s early concept name for the White Walkers, never born). In Game of Thrones alone, there is a foreboding connection between the undead leader and the Stark children. Whether he senses royal blood coursing through their veins (a la Melisandre), or he identifies them as his descendants, the Night’s King pursues both Jon Snow and Bran with increasing fervor.

In ASoIaF, Bran lends great verisimilitude as he reflects on the stories of Old Nan (who’s proving to be very useful all of a sudden):

“[The Night’s King] was a Stark, the brother of the man who brought him down.” [Nan] always pinched Bran on the nose then, he would never forget it. “He was a Stark of Winterfell, and who can say? Mayhaps his name was Brandon. Mayhaps he slept in this very bed in this very room.”

6. Warging the Wights

Wight Children at Hardhome Game of Thrones: 10 Things You Need To Know About White Walkers

While the White Walkers remain the preeminent threat to Westeros, their army of undead are unquestionably less tame. Throughout Game of Thrones, we have grown accustomed to reanimated corpses wreaking havoc on victims. Even the pilot episode introduced us to a blue-eyed wight bent on destruction. Only recently, however, have we begun to glimpse the larger tapestry of warging that the Night’s King and his pale riders can exact.

There are two key moments worth remembering: after the collapse of Hardhome, Jon Snow and his surviving companions drift into the water away from the sea of corpses. When the Night’s King approaches, he stares down the Stark boy and lifts his arms as if conducting an orchestra of death. In perfect rhythm, the wildings are raised from the dead. Later, in Season 6’s “The Door,” Bran greensees the Night’s King and his army gazing at him in unison. As only a warg can achieve, the “beasts” of the reanimated undead appear singularly focused on their possessor’s target, offering further evidence that they have been warged by the Night’s King. If this theory holds true, then perhaps the increasingly-powerful Bran will be able to interfere with the White Walkers and steadily subvert their army.

5. Language of Skroth

White Walkers Up Close Game of Thrones: 10 Things You Need To Know About White Walkers

The only sound more terrifying than three blasts of a sentry’s horn is the scream of a White Walker. Just ask Samwell Tarly, who witnessed their death cry at the end of Season 2. Like the strangulation of a thousand shrieking horses, the White Walkers have a canon of sound at their disposal.

As for their language, faithfully dubbed “Skroth,” the Walkers’ native tongue is fittingly frigid. As George R. R. Martin describes it, Skroth sounds “like the cracking of ice on a winter lake.” The HBO showrunners David Benioff and D.B. Weiss initially intended to incorporate Skroth, going so far as to hire David Peterson (President of the Language Creation Society and creator of conversational forms of Dothraki and Valyrian for the series), to help develop it. Instead, they opted for ambiance over aural communication, which perhaps only heightens the creep factor.

4. Vulnerabilities: Valyrian Steel & Dragonglass

Jon Snow with Longclaw in Game of Thrones Game of Thrones: 10 Things You Need To Know About White Walkers

“Kill it with fire!” Alas, the enemies of the ice appear relatively impervious to the flame (though a certain Targaryen will likely have a rebuttal to this claim). White Walkers are vulnerable to a handful of precious metals, as Sam, Jon Snow, and Meera Reed have all discovered. Dragonglass, the substance that helped create the White Walkers, is also a primary weapon to end them. The highfalutin, Westerosi name for obsidian, Dragonglass spells extinction for White Walkers on the receiving end. Contact with the substance will freeze Walkers to the literal breaking point, until they explode into minuscule ice particles.

Valyrian Steel, the second known rejoinder to White Walkers, offers an even more instantaneous kill. In addition to repelling contact with White Walker weaponry (compared to normal steel which breaks on impact), a swift blow of Valyrian steel will shatter White Walkers on the spot. Care for a reminder? Here you go, courtesy of Jon Snow and his Valyrian sword, Longclaw.

3. Bound By The Wall

The Wall from the Game of Thrones Titles Game of Thrones: 10 Things You Need To Know About White Walkers

With nineteen castles, scores of catapults, cranes, and even an apocalyptic scythe, The Wall offers a 700 foot-tall, 300 mile-long doomsday fortress against the White Walkers. Beyond its physical strengths lie something even more impenetrable: an intricate web of magic that repels creatures of mystical and inhuman origin.

Brandon the Builder opted for a blend of physical and alchemic strength, and given the 8,000 years that passed without visitation by those from the Land of Always Winter, he appears to have struck the right balance. As Sam tells Meera in the books, “The wall is more than just ice and stone. There are spells woven into it…old ones, and strong.” Like the magical limitations that once blocked Wights from the Three Eyed Raven’s cave, these spells hold strong over The Wall. Now that Bran has been touched by the Night’s King, however, could the magic of The Wall be compromised?

2. Different Aesthetics & Name in ASOIAF

White Walkers on Horses Game of Thrones: 10 Things You Need To Know About White Walkers

Though they are popularly referred to as White Walkers on Game of Thrones, George R. R. Martin first presented them in the novels as “The Others.”  To prevent viewer confusion, however, Benioff and Weiss elected to rename the humanoids to something more visceral and not dependent on capitalization.

As for their graphical depiction from novel to screen, it seems George R. R. Martin originally imagined creatures more magnificent and visually pleasing than their depiction in Game of Thrones. Working with comic-book artist Tommy Patterson, Martin reminded him that, “[White Walkers] are strange, beautiful…think, oh…the Sidhe made of ice, something like that…a different sort of life…inhuman, elegant, dangerous.”  The Sidhe that Martin mentions come from Irish mythology, representing an amalgamation of fairies and elves. For HBO, however, the White Walkers have become far more emaciated and frightening, like one of Ramsay Bolton’s flayed corpses dipped in snow.

1. Patterning of Corpses

Corpse Patterns Game of Thrones Game of Thrones: 10 Things You Need To Know About White Walkers

Recurring themes and tropes make Game of Thrones a true fantasy triumph. From book to screen, HBO and George R. R. Martin alike have remained dedicated to introducing juicy plot lines in their infancy and nurturing them into their prime. For the White Walkers, their killing is seldom random and unmotivated. Several masterful wide-shots throughout the show depict the bizarre, cult-like patterning of corpses left in the White Walkers’ wake. Even Mance Rayder takes note when finding a graveyard of horse corpses, dubbing the Walkers, “Always the artists.”

As with the first season of True Detective, symbolic patterning plays a role in Game of Thrones. Like the Milky Way-modeled organization of dead animals and the bodies in the pilot episode, Season 6’s “The Door” showed an eerily similar design around the Raven’s Weirwood tree. How fitting, then, that the White Walkers model their corpse patterns after the very people who created them…

Bonus: The Children of the Forest

Children of the Forest with the First Men Game of Thrones: 10 Things You Need To Know About White Walkers

As revealed just this last week, The Children of the Forest birthed the White Walkers as a failsafe against the First Men. By plunging a dragonglass blade into the (as of yet unnamed) man’s heart, they converted a human warrior into the Night’s King, born and bred to slay anything that threatened the Children of the Forest. This nuclear option ultimately backfired, however, as the blue-eyed humanoids ultimately became stronger than their creators. The Night’s King and his cohorts have only just begun to exact their revenge.

What else should we know about the White Walkers? Tell us in the comments section!

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