I think you're right about the princeley duties yea! I may be a bit rusty remembering all the details, it's the first time in 7 years that I spontaneously rejoin the fandom and start a new game (and I very very rarely replay games, or give up halfway point, so I think FFXV needs a special badge of honor from me, for tugging at my nostalgia so hard and pulling me right back for the whole road, where no other game could).
And that makes it even more ironic, doesn't it? For Regis to give Noct all the freedom for choosing his future (at least until he needs to take the throne and, yk...) and he willingly chooses the most strenuous profession. Which in this AU I think can work wonders for his character arc because we'd see him break right through the "lazy and indifferent prince" facade much earlier on and much more prominently. It was heavily implied at in the Brotherhood anime (ep 4 which i also rewatched the other day very perfectly timed lol) that Noctis avoids his duties, and is a general disaster, because he doesn't want to accept the future of his father dying and him taking his place, and instead prefers to disassociate from reality for as long as he is able.
And if he was studying to be a doctor, he'd really understand this fastly approaching inevitability of death, and it would be very hard to ignore it for long. I like to imagine that he wouldn't tell anyone (out of embarrassment or fear for making it real) but he would have his mind set on using the road trip as something of a side-hustle to find a cure for his dad (or something to help keep the Wall up without draining his life energy) and learn more about daemons as a whole to help heal injuries more effectively. This is where we'd get him acting immature as a teen/at the beginning of the adventure because every time someone would hint at "hey, yk your dad is like, doomed, right? you need to take your duties more seriously because who knows how much time you have left until you have to take his place," he'd be rightfully pissed/ snap/ stand his ground, but he wouldn't give away his actual intentions of curing him himself.
[note: this may sound unplausible but it makes sense in my head because i see Noctis having problems with showing affection and care to his father the more he grows up, and them drifting apart through the years as the fear of death grows stronger in Noct and his defense mechanism against it is to try his best to ignore it (and being close to his dad only serves as a reminder) and search for a work-around method without wanting to burden any of the people around him. so you have this sort of "avoidance love" relationship where Noct cares extremely much about his dad but is also extremely shit at externalizing it out of fear, social expectations, embarassment, and so on.]
More on my previous thought: if this is hypothetically implemented into the game, I think it would be a great fix for the ludonarrative dissonance you need to have to be able to fully immerse yourself in the story (i am very good at that yes) because you'd actually have a character-driven reason to take all the errand-boy side quests, as it would be Noct's way of dealing with the grief of Regis' death by sticking to his studies and his wish to help people by discovering more of the world and its creatures and how magic works on the field. I imagine it wouldn't be outright mentioned in the quest logs or objectives (because it would kinda kill the magic and make it less meaningful), but we'd get dialogue hints of Noct commenting on the stuff he finds and his friends trying to carefully approach the subject without being obtrusive or bring back old wounds.
So on your B) point: it is true, Regis and we as the audience know it, but Noct doesn't have a clue he'd need to throw his life away as a sacrificial lamb, he kinda gets the point from Chapter 13 onward. So until then, he works on the presumption that he has all the time in the world to make things right, and I think that gives great potential to his growth. His dad's worsening state would serve him as a grim reminder that the clock is ticking and he'd feel guilt over the avoidance of his duties but not enough pressure to act upon them. Reality is dawning on him by the minute, and just as he can finally start feeling useful/ like he's fulfilling his purpose with the trip to Altissia, then the Fall happens, and everything comes crashing back to 0. Mmm wanted to say more things here, but my brain crashed, I may come back to it when I clarify my headcanons.
I may need to brush up on the lore to comment on the relationship between magic and technology in Eos, I just don't remember how much was explained in the game and what part of it I know by fanfiction means heh.
Ok, you got me curious, have you seen the video essay "Final Fantasy 15 was a Mediocre Disappointment" by Super Eyepatch Wolf, first because it's one of my very favourite videos on the whole platform (and it's so soothing for bedtime story too), and second because he touches exactly on those worldbuilding problems, of course coming from a place of love. I absolutely agree with those points, I'm just more than happy to look past the flaws and enjoy meandering about the world, as vast and empty and illogical as it is in its structure. You can feel the steady foundation being there, waiting to be built upon and flourished, but I believe it's not for a lack of care that it's overlooked and rushed and plastered with meaningless buildings for the sake of gameplay, it's just the time restrictions and the disaster of resource management in the development; hence all the copy-pasted locations like diners and gas stations with little to no protection against the wild fiends, and the people feeling like being picked up from a generic commercial center and plastered upon this dangerous world.
I don't hate it, I don't love it, I wish we could have had more, but I'm content with working with what we got. The relationship between the boys and their story is enough for me to feel a connection to this broken world, and I look at it as a playground where I can imagine what could have been and what can still be. I'm heavily biased from my love, but I'll protect this game to the end of my time, even if it means looking past the break of immersion in the world itself.
[eh there's a lot more eloquent people that me that can say it better, you don't have to watch it of course, but I recommend another video essay titled "I Can't Stop Thinking About Final Fantasy 15" by Big Shwong, which is essentially a love letter to the game, and surprisingly, especially to Eos. It took me so hard by surprise that someone would genuinely adore this world so much that this was my drive to get back into the game and experience it a second time around with new perspectives (and ofc miraculously find this post because I was wondering if the fandom is still alive and kicking)]
Ok I'll cut myself short here so this is not overwhelming to read in one go, but I'm gonna be thinking about this all day trust!
