In the first episode from the eighth and final season of television’s reigning fantasy epic, errant knight Jaime Lannister (Nikolaj Coster-Waldau) finds himself facing fellow noble Bran Stark (Isaac Hempstead Wright) for the first time since Jaime threw the then child from a tower window in the show’s 2011 debut episode. Bran had accidentally witnessed Jaime having sex with his own sister, now the realm’s queen, Cersei (Lena Headey), and the boy subsequently lost the use of his legs in the fall. Since then he has survived an attempted assassination, years in the wilderness and an undead attack, before gaining mystical powers from the Three-eyed Raven (Max von Sydow), an ancient seer fused with a holy tree. Jaime, for his part, fought in a war, had his sword hand chopped off, and lost to grim deaths all three royal children he illicitly fathered with Cersei. Obviously that’s just a broad outline.

At this ludicrous yet portentous point, Game of Thrones (screening on Foxtel), a medieval drama set in a fictional world suffused with magic and human failing, is an uneasy mass of intricate plotting and weighty expectation. After a long and bloody struggle for the throne of the island continent of Westeros, the survivors from the aristocratic families, exiled usurpers and sundry provocateurs are united against a common foe: the undead hordes returned from ancient myth to destroy the living. Joining bitter adversaries together – with their armies, dragons and barely contained enmity – is a celebration of the show’s Darwinian drive. Only the strongest, cruellest and most devious remain standing.

The vast commercial success of the HBO series allows it to be magnanimous. This season’s first episode jokingly referenced the show’s former habit of using “sexposition”, where story points were advanced in the company of naked women. Other lessons learnt along the way have been taken seriously, such as not depicting brutal scenes of sexual violence from the aggressor’s viewpoint. Game of Thrones has cut those back, while female characters have risen to positions of power (although only those born with privilege have any agency). Apart from a few awkward diversions, the experiences and voices of ordinary Westeros people have been marginalised – they’re apparently just waiting to be ruled.

The show’s mood is martial now, with fewer debates about the moral quandaries of seeking power and more tart acknowledgments of keeping it. “What do dragons eat, anyway?” asks Sansa Stark (Sophie Turner), the host of this shaky coalition. “Whatever they want,” replies Daenerys Targaryen (Emilia Clarke), the imperious “mother of dragons”. Later, Daenerys enjoys a quick date with Jon Snow (Kit Harrington), where she establishes her power credentials by letting him ride her spare dragon; the digital beasts give more convincing performances than the two actors.

But, with the weight of the previous seven seasons’ 65-odd hours of thwarted heroics and cruel tyranny, there’s an undeniable momentum to Game of Thrones and its looming finale. Despite the planned prequels, it may well be the last show people obsessively watch around the world at the same time. Author George R.R. Martin, who has been publishing the source novels since 1996, drew from such a rich foundation of texts – including Tolkien’s Middle Earth and Shakespeare’s The Wars of the Roses plays – that it can’t help attain a suggestive resonance. After all, rival factions having to confront an existential threat speaks overtly to today’s climate change crisis. Sadly, only the television show will get a succinct resolution.