Garrosh was a character I loved to hate. I felt that you were supposed to hate him during Pandaria, but he was more of the "traditional orc warchief" in Wrath and Cataclysm. What I mean by that was that the original horde, the one that followed Hellscream through the dark portal 30 or some odd years ago did so simply to conquer Azeroth. They were DICKS, irredeemable dicks, and their actions led to Varian and many others' hatred for orcs, even the calm(ish) ones like Thrall. Even IF Grom redeemed himself at the end of Warcraft 3, it made for petty justification.
Garrosh was a Warchief in a literal sense, but Thrall had turned the term into something else, a leader of a band of cast aside misfits that became family. Garrosh betrayed that trust, but it wasn't entirely his fault. From day one of Cataclysm, Garrosh was met with internal strife. Vol'Jin threatened him with assassination instead of lending his words of wisdom as a counselor, and Cairne challenged him to a duel because he thought him unfit to rule the Horde.
In the end, I believe he truly thought he had no allies left within the horde and he turned to the Kor'kron to create the true horde. When that failed, he was left in chains, only to be freed by Wrathion and sent to Past Draenor. Then he met Thrall, who absolutely refused to claim any responsibility for making him Warchief during probably the worst event in the world's history, with "allies" who would sooner stab him in the back than give him guidance. In the end, Thrall would rather kill Garrosh than try to make ammends. They were friends once. There was a time where Garrosh would actually sit in the same room as Jaina with a straight face. He was not an irredeemable villain, and he killed him anyway.
"It's such a fine line between clever and stupid."
The Chronometal Wars, a fan-fiction taking place in the PPGD Universe. Catastrophe is the only certainty.