@Darketower exactly, finally found someone realizing this, I thought I was the only one in the world... Behavior is extremely driven by you brain's chemical balance, yes you can pretty reliably control sudden ups and downs, but if you are constantly barraged by chemicals during medication or as in isekais, transported to a body of a teenager you WILL change, your view of the world, the way you act and your values will change with you (and in the isekais it never happens).
You can take examples out of life where pretty much every teenager (unelss literally mentally ill) cares about his school reputation and is very emotional even if he pretends not to be (since it is perceived cool), when later in the life people literally stop caring about the others...I don't like how people like to call it "growing up out of it" or "maturing", we know how some people don't really change... it is just that their chemical balance in brain changes and so they change with it
You can take examples out of life where pretty much every teenager (unelss literally mentally ill) cares about his school reputation and is very emotional even if he pretends not to be (since it is perceived cool), when later in the life people literally stop caring about the others...I don't like how people like to call it "growing up out of it" or "maturing", we know how some people don't really change... it is just that their chemical balance in brain changes and so they change with it