I don't no if this is a off-topic question but the main doubt, in my opinion, is solid on the character development tag.
So, maybe the concept of Conflict, which I'm comfortable with, will sound divergent from yours. I think that this is a technical minor aspect, but I feel that in my doubt this will make some difference.
In my textbook  the author treats, as expected, the whole concept of Conflict in character development. But he treats the particular point of "Inner Conflict" in a huge different manner: something more fundamental than the external conflict or even internal conflicts of the mind of the character. For him, the "Inner Conflict" is called "fundamental essence". This fundamental essence is even beneath Inner Conflict of the mind of the character (and clearly beneath the external conflict). This fundamental essence is the prime cog on character behaviour in story, something "raw"; knowing this fundamental essence the author can forsee the attitudes of an character face a particular situation or, in other words, the author can say for sure:
"Oh character X will never do this!"
The textbook exhibits an example of a "conrete" fundamental essence:
O God! God! How weary, stale, flat and unprofitable, Seem to me all the uses of this world! Fie on't! ah fie! 'tis an unweeded garden, That grows to seed; things rank and gross in nature Possess it merely.
The textbook says then that here we can identify the fundamental essence of Hamlet's: Hamlet extend his feelings to everyone when he says "Fie on't! ah fie! 'tis an unweeded garden, That grows to seed; things rank and gross in nature", then due to this the essence is settled and then he is "ready" to inner and external conflict.
Well, this is a nice pedagocial example, but still, I do not understand quite properly. In order to understantd Fundamental essences in characters, I would like to shift the story to another which I'm quite familiar: Star Wars. So, the story is different but the need for a Fundamental essence is conserved. In the context of "Fundamental essence", what is the fundamental essence of Luke Skywalker?
 Luiz Antônio de Assis Brasil, Escrever Ficção: Um Manual de Criação Literária, Companhia das Letras, 2ed,São Paulo,2019.