A little confused about supplanting
One thing that I really wish was touched upon more is the act of one being supplanted. Like, I understand it at a basic level. Someone will have a bad life, do something awful, or something else along those lines and surrender their old life for something new but fake. However, I never got exactly how anyone who was supplanted could live a new life.
The Thunderhead alerts the supplanted person that they had been supplanted and that they're someone new. But, what about connections with other people? If every new memory that a supplanted person has is fake, how does one have a family? You're an adult and have memories of you as a kid opening presents with their family on Christmas, but that family does not, and has not existed.
Your mother's name was Julia and you cannot find her for the life of you because she was not real. Wouldn't that be soul crushing? The homecoming kiss with your crush? Yeah, that was fake. You have a vivid memory of you giving a speech at your best friend's wedding, but everyone in that room or venue is not real? They could not be real, 'cause if they were, then they would have no memory of you at all, because they do not know you. Does the Thunderhead supplant multiple people to share a memory? Does the Thunderhead supplant two people into having a marriage as to give you a memory that is "credible?" Then, wouldn't that impede of free will? Having a marriage that you remember happening, but it never truly did? The Thunderhead puts you with someone you truly never knew and you never got a say in it? Granted, you could make the argument that the Thunderhead makes the correct decision every time, so the person you'd be married to would be ideal, but correctness does not equal right all of the time.
Perhaps I'm looking too deep into it, but I really wish there was a deeper look into supplanting.