you made a very good socionics argumentation. well done.

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I personally can't really see Finn as a judger. All too often he just goes along with some spur of the moment ""plan"" - pretending to be with the resistance, helping Poe in TLJ, deciding to sacrifice himself. None of these are really planned in advance, but rather, Finn just comes up with them on the spot. He is probably a 6w7 (as hearts made a great case for), so he can be hesitant and concerned and skeptical at times, but I really think he naturally operates on a more improvisational basis. I'd type him as some sort of xxFP. E/I and N/S are hard to tell, but rn I sorta think xSFP might make the most sense. He's typically not a big idea kind of thinker, but more focused on the simple things - comfort, safety, people he cares about. He's really not that "deep". He also doesn't really have the impulsive or reckless characteristics often associated with Se, but imo he takes on the "9-ish" Se characteristics more than the "7-ish" Se characteristics, in that he's often very focused on the moment and his present desires and goals. He's often improvisational, as I said, but not really in an Ne-ish idea-bouncing sort of way.

I don't usually type using socionics because I feel I don't know enough about it yet, but SEI seems about right, and I think that might describe him better than any mbti type. He doesn't really have much mbti Si, but he has tons of socionics Si (very comfort-seeking, focused on his own personal needs and desires over a bigger agenda (at first), avoids and runs away from the things that make him uncomfortable).

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I think, in a lot of ways, both The Last Jedi and The Force Awakens are focused on exploring our (often times complicated) relationship with The Past. Kylo Ren is consumed by the burden of his family's legacy. Rey and Poe are both obsessed with the tales and archetypes of the old rebellion and end up caught up in their own hero worship and desire for the external validation of these old heroes. 

But Finn is anamolous in this regard. On some level Rey, Poe, and Kylo are all operating on the basis of some conflicting ideological principle. Rey wants to be Important - to have her legacy validated. Poe wants to be the Hot Shot Flyboy that saves the resistance. And Kylo wants to destroy the past's control over his identity and sense of self.

But Finn doesn't really buy into any ideology - not until the end of TLJ. Finn's motivations always come from a personal place of conflicting loyalty - firstly to himself and secondly to Rey. He's a lot like Han Solo in this regard - Finn grows into a loyalty to the resistance but only after seeing firsthand what a primarily you-centric worldview leads to -- in other words, DJ.  

Finn is highly skeptical in this regard - he is someone who is looking for something (or someone) to believe in and support. And once a person (or principle) has crossed his threshold for belief, he will go to any lengths to protect it (or her). Finn is notoriously non-commital to the efforts of the Resistance at first -- unlike what I would expect from a 9, he does not simply go along with the agendas of the people he's around to maintain harmony. In fact, he actively resists and tries to defect in order to go after the person he actually believes in - Rey. 

The Last Jedi's priorities for Finn are largely about the pratfalls and the psychology of his radicalization into the Rebellion. Like his relationship with Rey, once he has decided the Rebellion as something worth believing in, he is willing to go all the way. He is willing to integrate fully into the Rebel mindset and sacrifice his life and love  for a cause he was previously ambivalent about - once that cause proved it's underlying worth and value as something worth protecting. His relationship with The Rebellion mirrors his relationship with Rey in the first movie - he goes from largely self-interested to fierecely, intensely loyal to something beyond himself. 

Finn's arc both in The Force Awakens and The Last Jedi seem much more compatible with a 6 mindset than a 9 mindset. 

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