Think of Michele as a cult leader and Psyche his single, loyal follower. Cultists are vulnerable people who are manipulated into believing and doing things that just going make sense, and from the outside it's easy to say you'd never be in their position. But you never know.
THIS!!! omg, I dont think ppl understand that psyche barely has any knowledge of ANYTHING except for the cruelty he's experienced and the salvation his brother promised. to call him dumb for not even questioning his brother or his integrity/character is like asking someone to believe the sky isnt blue. we've only seen the sky blue just like how psyche has only seen his brother being kind. he's only just now being told that everything he knows is wrong and its not unreasonable for him to have difficulties processing it, especially when he's yet to directly see any evidence of his brother being the horrible person everyone is saying he is
It's easy to get annoyed by Psyche, yes, but consider his circumstances. He first spent a majority of his life not only being simply shunned, but hated, with the only person providing positive interaction for him being his brother. That is absolutely insane, I don't even want to think about how deep of a reliance he built on that bastard as a result, but I guarantee that's why he was even giving him crumbs of interaction in the first place while simultaneously not intervening in his siblings' cruelty.
And then, after that absolute mindfuck of an early childhood, he's then thrown into a tower and locked up with his only hope of rescue ALSO being the person he had developed an incredible emotional dependency on. It doesn't matter what people are saying to him now after 10 years of confinement. To accept a piece of information that completely topples what is realistically the fundamentals of his incredibly tiny world is nigh impossible, not this soon. Hell, one of the first things he saw after 10 years of isolation is his brother's head on a stick and everyone around him saying they outta kill him. I would be reluctant to open my heart and mind up to them too.
Y'all are asking so much from someone who knows absolutely nothing of the world in the most literal sense. At least give him a chance to grow.