Despite what had went on between the brothers, what Thor actually experienced, there was little anyone, including Lucifer himself, could do to shake Thor's ever lasting faith in his brother. He knew what was supposed to happen in his future, in New York, but, as he'd told himself many times, that didn't mean that it had to happen when he returned. He told himself that he would know to search for Loki, to not assume that he was dead. The fact that everyone told him that you didn't remember being here or anything you learned just made him more determined to actually remember such things.
That did not mean that these images weren't terrifying to him. To have been told second hand was one thing, but to see it was something completely different and unexpected. It made him nauseated to see his brother act in this way. All he could tell himself that this person was not his brother, not the one that he had grown up with and still loved dearly. It appeared as though Loki had sunken into complete madness. He could still hear the argument with his brother on that mountain, still hear the caw of the ravens that flew around. He could see the devastation of New York around him, his brother laughing maniacally, and him pleading for his brother to see reason, before Loki stabbing him in the stomach with one of his knives and escaping.
It wasn't just when he slept. Every time he shut his eyes he could taste the acrid dust in his mouth, debris having gotten into the air of the city from the destruction around them. He got no peace from it.
He was sitting alone in his room when Loki arrived. Loki arrived without a sound, as per usual, but Thor felt it when he arrived, looking up from the spot on his bed where he had been sitting. "Thank the Norns that you have come," he said.