[Medium spoilers] On Draenor B, Garrosh was never born.
Reading through new short story, Hellscream, and found this of note:
"I understand how you feel." Garrosh chose his words carefully. "My father died with his axe buried in his enemy's chest. A good death. But the path that led him there was paved with dishonor and was born from a single wrong decision. For too long I lived with rage toward him. It was wasted anger. Your mate's death and your clan's moment of weakness may still cause you pain, but the son she gave you—"
"My son? She never gave me a son."
Grommash was staring into Garrosh's eyes, weighing him, judging him. Garrosh did not even allow himself to blink. "I did not know that," was all he said.
Kairoz. Garrosh felt a cheek muscle jump. Counting blades of grass. He took a moment to relish the memory of carving out the dragon's middle, feeling Kairoz's hot blood flow over his hands. It calmed him. Deep breaths. I was never born on this world. Grommash was never a father. Is this what the bronze dragon meant by "the perfect timeway"?
Kairoz tells Garrosh to not worry that this Draenor is not exactly the same, and it's revealed that Garrosh's mum didn't die honourably, and she bore no son.
Is this a surprise? I haven't read anything longer than this story, or played WCI, II, III, so am unaware of how old Garrosh B would be.