
Well, it’s not like they always show a more younger mindset. It’s only when they have to put their trust into someone else that they revert to blocking everyone off and just trusting each other. The author doesn’t need to tell us that when they literally show it. They were pretty happy normal 18 year olds back in their original world. Also 18 is also pretty young too. You’re still a teenager back then. No one looks back to their late teens and thinks, “Wow I was SO mature back then.” They never experienced “the real world.” And then they come into a new world where they have to deal with nonstop abuse for 5 years in much weaker and easier to control bodies. You’re bound to have trust issues cuz of that. They don’t think ahead because they are too busy focusing on surviving the present with one another and deciding who is trustworthy purely based on how nice they seem. They don’t any of the information the readers know about the Duke Rosea. He’s nice to their faces and they aren’t used to adults being openly friendly to them in this world so that’s a good enough reason to trust him. And as for their father. He literally wasn’t there when they had to deal with the most trauma they ever faced in both lifetimes. To them, he’s just deadbeat dad that finally decided, “Aight time to pay child support I guess.” And honestly, it’s kinda his fault that they are misunderstanding everything. He isn’t tell them all the whole story either because he sees them as just regular 5 year olds with their imperfect manifestations. It’s just miscommunication from both sides.
They r not even mentally young so why can’t they think ahead on almost anything . The older brother who’s actually younger than them is more sensible atleast .