Game of Thrones finally delivered Cleganebowl, and although both Sandor and Gregor died, it's fair to say that the Hound won against the Mountain. One of the most popular fan theories that's ran since the very early years of the HBO show has been that the Clegane brothers - Sandor aka The Hound (Rory McCann) and Gregor aka The Mountain - would have an epic showdown.
After many near misses - most fans got hype for the duo showing down for Cersei's trial against the faith militant, which never came to pass - it finally happened in Game of Thrones' penultimate episode, "The Bells". As King's Landing burned and the Red Keep collapsed under Daenerys' dragon attack, Sandor confronted his brother (along with Queen Cersei and Qyburn) in a crumbling staircase. After the Hand of the Queen was dispatched by an angry Mountain and Cersei snuck past, the pair finally fought.
Cleganebowl ultimately saw the death of both Gregor and Sandor, with the latter pushing the former through a weakened wall down to the fiery depths below. But while the two brothers died, there's no denying that it was the Hound who won: he finally overcame the brutishness of his brother and his lifelong fear of fire.
The Hound has been a primary character since Game of Thrones' premiere, initially Joffrey's bodyguard. the Mountain was introduced a couple of episodes later, and with it the brothers' rough history: as a child, Gregor held Sandor's face against a fire, permanently disfiguring him and leaving him afraid of flames into adulthood. As the Hound evolved into a more sympathetic character, it became clear that the major barrier to his arc was his brother. A fight between the two was always more than internet memes.
To the surprise of no one, when the battle began the Mountain had an immediate upper hand. He's not had as much character development across Game of Thrones, but makes up for that by being an ungodly zombie after dying from poison care of Oberyn Martell in Tyrion Lannister's trial by combat; as the Hound says, Gregor now looks on the outside as he always was on the inside. This magic resurrection meant that the Mountain was able to withstand stabs to his chest and face without as much as a wince - and he almost repeated the Oberyn melon-head trick. Essentially, he was unstoppable in direct combat.
These two arcs - one a thematically rich character journey, the other a removal of the outer facade (indeed, Gregor gradually shed his armor as the fight progressed) - are what made Cleganebowl feel so satisfying, and allowed the Hound to put it to an end. He stood up to his towering brother, accepted his fate, and conquered his fear. That involved his own death, but as he said to Arya before they parted ways - with her calling him by his given name in a show of respect - that was an inevitability. In amongst the tragedy of the battle of King's Landing, this was one aspect that is tinged with victory.
Game of Thrones concludes next Sunday at 9pm on HBO.