I like to think the Loki is always thinking about, always remembering his childhood. His past. Because it was peacful, his childhood with Thor. When he wasn't a monster but instead a child, a kid, Thor's brother, Odin's son. He thinks about that to keep him going, to give him motivaion. He remembers how much they lied to him, how differently they treated him. Even if it didn't happen but it;s stuck in Loki's mind, he holds on to those thoughts and uses them to power him, to push him forward. If he falters from that path for more than a second, he'll remember those times.
And I reckon it drives Thor insane, because he knows about it. Because he knows that it is him motivating his brother to destroy and kill. Thor knows that it's mainly his fault that Loki is as he is. Not that he could have done anything about it, it's just how things are. Thor got the throne and Loki didn't. But it's more than that, it's the fact that his childhood was peacful and then sort of taken away from him.
I dunno, just a random thought.
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