Warning: Spoilers Ahead For Game of Thrones season 8, episode 1.
The Game of Thrones season 8 premiere revealed a huge amount... including a new potential meaning of the "ice and fire" that is so important to the series: what happens when forging dragonglass. The HBO series may be called Game of Thrones, but the original book series by George R R Martin is titled A Song Of Ice And Fire, and while plenty has been changed from page to screen (as happens with any adaptation), the importance of ice and fire is still central. It's popped up in the marketing, the fan theories, and so much more - even though no one seems quite clear what, exactly, the song of ice and fire actually refers to.
The biggest thing referenced when talking about Ice and Fire is a vision that Daenerys has in the House of the Undying. This vision sees Rhaegar talking about a newborn child, named Aegon, saying "He is the prince that was promised, and his is the song of ice and fire". This vision could connect to the legend of Azor Ahai (also known as the Prince that was Promised) as well as to Jon Snow, who has now been revealed as Aegon Targaryen. Other possibilities include the theory that "Ice and Fire" refers to a Stark and a Targaryen - first Lyanna and Rhaegar, and now Jon and Dany (assuming that Jon still counts as a Stark thanks to his mother and how he was raised). A final major assumption is that it isn't about specific people, but about the battle between the magic of fire (dragons, dragonglass, and potentially Valyrian steel, given the connections between Valyria and fire magic) and the magic of ice (the White Walkers and the wights).
The Game of Thrones season 8 premiere has another moment that references ice and fire - although it's a blink-and-you'll-miss-it one. When Gendry is in the forges at Winterfell, he is seen making weapons out of dragonglass, forging it like metal. However, unlike metal, when it is heated it turns blue, before cooling to black.
This isn't something that happens with obsidian in the real world, so it's been added by Game of Thrones in order to create a cool visual effect - but also to connect it to ice and fire. The color blue is strongly associated with the White Walkers (and their blue eyes), who were created with a dragonglass weapon by the Children of the Forest. The shot that shows the contrast between the glowing red crucible and the blue of melted dragonglass couldn't be a clearer reference - but is it an important one?
It's possible that there is even more to dragonglass to be revealed (that will be important to the plot of the final season), so this could well be the first shot that will hint at its connection to the Prince that was Promised. While plenty of characters have Valyrian steel swords (and even a flaming sword), perhaps this hints that Azor Ahai can only use a weapon made of dragonglass. Of course, it may be nothing more than a really cool shot that connects back to so much of the ice and fire marketing, or just a way to remind fans that dragonglass weapons are being forged, not just metal ones, and to hammer home its magical nature and importance against the White Walkers. But in Game of Thrones, nothing is ever as simple as it seems.
Game of Thrones season 8 airs Sundays at 9pm on HBO.