In the aftermath of Loki's fall (and Thor can think of it as nothing else, whatever others may call it) there are many versions of the event, and they spread through Asgard as quick as a northern wind.
He enjoys the more outrageous ones the most, they are the sort Loki himself would spread were he there.
The truth tho is hard to find. It always is when Loki is involved.
But Thor has never needed to know the truth to believe in his brother, because there is one thing that Thor knows, that Thor will not doubt, even if it seems Loki himself may be doing exactly that; Loki loves him.
It is almost a week after Loki's fall when Thor hears both the best and worst news he can think of. Loki is not dead, and there is no way for Thor to reach him, not until the bridge is fixed, or the Lady Jane succeeds in building her own.
Thor destroys his room. His furniture lays in ruins and walls shake with his rage.
It does not bring his brother back to him.
He falls to his knees among the wreckage, and hangs his head in silence, his breathing a ragged, choked thing that seems torn from his body.
Loki is the most intelligent person that Thor has ever met. If their situations were reversed, if Thor had been the one to fall, Loki would do whatever he had to to find him, and Thor does not doubt that he would succeed, whatever obstacles he may have faced along the way.
Thor is a man of action. He does not possess the affinity that his brother has with magic, or have the knowledge he has gained, but he is at least as stubborn as him.
Loki would find him, and Thor shall do no less.
Thor begins by doing something he has not done in centuries. He brakes into his brothers room and goes through his belongings.
It is months before Thor finds it, hidden pathways between the worlds, pathways that do not require the building or repair of bridges that will not be finished for years to come.
It will take him more months still to learn the pathways, and even still it will be dangerous to travel them, but for Thor there is never another course of action.
He will find Loki and then...
He will find Loki and then he will do what he must, just as Loki would do for him.