Irreversible change

Alright hear me out on this one: A fantasy setting where a common theme is that of choices being irreversible. This would include things like only being limited to one type of magic, kingdoms opting for a cruel reign but unable to change for the better, etc. I'm merely struggling with why this has to be.

Here's my two cents.

Logically, and philosophically, how would this work? Technically, all of our choices are irreversible and cost something, in the strictest sense. I made the choice to start typing out this post instead of looking for something to do at work. I could stop at any point, or delete what I've written and close out of TV Tropes, but I can't get back the time and mental energy I expended here, formulating what I'd write and thinking about your post. In your world, would I be required to see my post through to completion? The whole discussion? To what degree of completion? And what would happen if someone else made the choice to stop me from continuing my post and carrying out my choice? What if my computer suddenly BSODs, or the internet goes out, or the site servers go down, or we get hit by a solar flare that takes every computing device on the planet out and irreversibly wipes the whole internet from the face of the Earth, or any other adverse condition preventing me from carrying out my choice that had no choice or will behind it? And technically, my choice to work on this post instead of actually working at my job conflicts with my manager's choice to hire me so I can benefit the company, and my choice to come in to work today for the purpose of doing work.

Being limited to one type of magic could easily just be a simple limitation of the magic system (your body changes to accommodate one type and that's that), but what of the kingdom? Is the choice to bring a cruel monarch to the throne or El Cruel's actions not in conflict with the overarching choice by the kingdom's other statesmen, or even the kingdom's founder to uphold a just monarchy, or maintain the state of the kingdom? There had to be others who made choices to put someone other than El Cruel on the throne, or made choices antithetical to El Cruel's ascension, so who or what decided that someone's choice to have El Cruel ascend should be irreversible and the result immutable? And presumably, nobody literally made the choice to put just some random cruel person on the throne, they wanted El Cruel specifically because they supported his politics, or were his personal friend. If someone's choice nonetheless decrees that El Cruel must remain on the throne and his choices are law, what's stopping some disgruntled statesmen or servants or anybody from trying to change his behavior or offering him preemptive advice with their reports to him, to try and prevent El Cruel from making cruel choices? What's stopping the people from clothing their opposition to El Cruel's rule in several small goals that don't violate the decree of El Cruel in isolation, but when taken together undermine El Cruel's cruelty? And presumably there's nothing stopping the kingdom's subjects from fleeing El Cruel, because the choice only seems to apply to the kingdom itself.

It's a bit fraught, from my perspective- I see this less as a question of what made the world this way in the first place (given that there's magic, it could easily be the work of a pissed-off god of fate), and more one of how this would even work from a logical standpoint. Applying this to an individual choice that affects no one else like choice in magic is a limitation that invites conflict, but the kingdom situation specifically as you describe it, with the kingdom unable to ever change things and stuck with an immortal El Cruel on the throne or every king destined to become the next El Cruel sounds antithetical to conflict. The heroes cry over it a bit and leave, or they completely violate the point of having a choice-driven immutably cruel rulership by sacking El Cruel anyways and putting a nice guy on the throne who stays nice. And when you consider loopholes like what I mentioned above, it becomes increasingly implausible that El Cruel in particular could have wound up being choice-driven to the throne in the first place, or would stay for long.

Well uh... I didn't mean it quite that literally. I was basing it on the idea of choices but mainly that of consequence. Once a desiscion has been made and your mind has been made up about it there's no turning back, those kinds of things.

So everybody is very impulsive and stubborn?

No you misunderstand, I mean the points of interest in the setting would follow those themes.

Then that's history as we know it. Any action worth noting is impossible to undo. Even an attempt would cost more than if the action was never done.

If I understand you correctly, you want to introduce thematic symbols of choices and consequences into the background of your work? That's usually done with bitter, older characters who made some unfortunate choices in the past, and no longer have the willpower to undo them. Sometimes the protags are members of a younger generation who rebel against these choices, either successfully or not. "Romeo and Juliet" is the Ur example. The original Star Wars trilogy fits this pattern, as does Lord of the Rings. Partly it depends on how far back in the past the plot relevant choices were made. If within a generation, then the person who made those choices can be a secondary character. If in the ancient past, then ruins and tomes and legends told around campfires can work as introductory devices.

See that's more like it, I was asking for examples and you gave me one. People should really try to be more helpful.

This is a setting board. We all thought you wanted help with the setting not the plot.

Technically, he wanted help with thematic elements. Unfortunately, we don't have a dedicated thread for that.