É apenas uma coisa do Gregor

Vou reiterar o meu ponto de mais cedoGeorge RR Martin escreveu Gregor Clegane como um "bruto assassino":

He's a murderous brute, and really needs no reason to kill someone.
^{-So Spake Martin http://www.westeros.org/Citadel/SSM/Entry/Asshai.com_Interview_in_Barcelona.}

Imagine quanto mais assassino e brutal ele é revivido como uma versão morta-viva de si mesmo. O GRRM também disse sobre aqueles que sobrevivem à morte que:

My characters who come back from death are worse for wear. In some ways, they're not even the same characters anymore. The body may be moving, but some aspect of the spirit is changed or transformed, and they've lost something. One of the characters who has come back repeatedly from death is Beric Dondarrion, The Lightning Lord. Each time he's revived he loses a little more of himself. He was sent on a mission before his first death. He was sent on a mission to do something, and it's like, that's what he's clinging to. He's forgetting other things, he's forgetting who he is, or where he lived. He's forgotten the woman who he was once supposed to marry. Bits of his humanity are lost every time he comes back from death; he remembers that mission. His flesh is falling away from him, but this one thing, this purpose that he had is part of what's animating him and bringing him back to death. I think you see echoes of that with some of the other characters who have come back from death.
^{-http://www.maximumfun.org/sound-young-america/george-r-r-martin-author-song-ice-and-fire-series-interview-sound-young-america#transcript}

Isso é repetido várias vezes com Gregor, dado o quão morto ele estava e o quão concentrado estava em sua raiva contra seu irmão, Sandor.

Você deve se lembrar que essa não é a primeira vez que ele desobedece às ordens e ao protocolo para perseguir Sandor, na Temporada 1 de Game of Thrones (e o primeiro livro relacionado, As Crônicas de Gelo e Fogo: A Guerra dos Tronos), ele ataca e quase mata ninguém além de Sandor Clegane, durante o torneio da mão.

Sua rivalidade é construída há muito tempo, tanto no universo quanto fora do universo.