Warning: This article contains SPOILERS for Game of Thrones' season 7 premiere
The season 7 premiere of Game of Thrones set the scene for the rest of the season, featuring a moment or two with almost every character. Each of the surviving Starks appeared and we saw Cersei plotting in King's Landing, but the biggest moment by far goes to Daenerys and her entourage coming ashore in Westeros. So momentous and long-awaited is the occasion, the episode is named for it -- "Dragonstone."
A tiny island off the eastern coast of Westeros, Dragonstone is the ancestral home of the Targaryens. It was there that the Targaryen family relocated to escape the Doom which destroyed Valyria, from there that Aegon the Conqueror launched his invasion of Westeros, and there that Daenerys was later born. Though the island and its castle were most recently in the possession of Stannis Baratheon, Dragonstone is very much a place forged by the Targaryens and the dragons they bred there.
The island is also home to an active volcano, making it not only a great location to hatch dragons but a good place to find obsidian, a naturally occurring volcanic glass formed when lava cools very quickly. The Valyrian word for obsidian translates as "frozen fire," but it's also known by a more common name in Westeros: dragonglass.
Dragonglass has cropped up in Game of Thrones on a few occasions: Sam discovers a stash of dragonglass at the Fist of the First Men and later uses a dragonglass dagger to stab and kill a White Walker; and more recently, Bran learned that it was through embedding dragonglass into a man's heart that the Children of the Forest created the first White Walker. The exact magical properties of dragonglass remain a mystery, but it's clear that they -- along with Valyrian steel and potentially dragonfire -- are one of the few materials capable of harming and even killing a White Walker.
As we saw in tonight's premiere, Jon is making getting more dragonglass his top priority, understanding its immense value in the coming war with the Night King. Luckily for him, he has a man down in Oldtown who knows exactly where to find a whole load of dragonglass -- Sam, who while reading through a book he swiped from The Citadel's restricted section had his suspicions about Dragonstone being home to a stockpile of dragonglass confirmed.
However, the news that there are piles of White Walker-murdering dragonglass just waiting for him on Dragonstone does come with a caveat -- the recently arrived Daenerys. In order for Jon to get his hands on any of that dragonglass, he'll need to strike a deal with Daenerys - one that will likely lead to the two forging an alliance. Will she agree to let Jon rule as King in the North? She did agree to support Yara's claim as ruler of the Iron Islands, but that was in exchange for a fleet of ships. What does Jon have to offer her - or will she demand Jon bend the knee? Daenerys can be rather convincing when she needs to be, plus she has three very large dragons and the very supply of dragonglass Jon so desperately needs. Declaring his loyalty to Daenerys in return for the dragonglass may be an offer he can't afford to refuse.
No matter how Jon decides to approach the situation, Dragonstone's supply of dragonglass will be crucial in the war with the Night King and White Walkers. There are very few Valryain steel blades in existence and the magical means used to forge them were lost in the Doom of Valyria. And while dragons once again fly the skies above Dragonstone, there's no guarantee Daenerys will send them to fight the White Walkers. The only hope anyone has of surviving the long cold night is to arm themselves with frozen fire.
Game of Thrones season 7 airs Sundays at 9 Eastern/8 Central on HBO.