Where Jim is not able to beam back aboard the Enterprise of his universe with the rest of his crew.
So he ends up stuck with a man that is so like and so unlike the one he knows. A Spock with harsh principles and a fierce, almost brutal efficency. Who knows, logically, that peace is the better way, but never experienced peace of mind himself. Jim’s only option is to find a way to stay long enough alive to reach the Guardian of Forever. He can only hope that Spock will not betray him, while he tries everything he can to not become his alternate self.