Love this! Royal arranged marriage and childhood mistreatment is an interesting combo. Exactly the type of IF I've been looking for, not necessarily y'know, the torture... but a royal MC that doesn't get to truly live as royalty. There are some similar plots where MC is unwanted by their family but I can't think of any where they're literally locked away.
The idea that MC's father is so traumatized over his wife's death he does a complete switch (I'm assuming he wasn't always a piece of shit 😂) and locks away the very last piece of her- the piece she died to create and provide for him- is so compelling!
Revenge would be a nice option but this also makes me wonder if we'll be able to forgive him in some way? Not entirely, but for an MC to understand why he got that way. Not because I actually feel for him but I like playing MCs that are insanely naive/kind to a fault. Ones that think everything should be sunshine and rainbows, and that a big hug and some love will solve everything 🥺