Dominant Function, Introverted Sensing, Si: Introverted Sensing is quite a personal and subjective function. What this means is Si takes in information in the form of facts and memories on topics that are of personal importance and interest to the dominant user of the function. This kind of honing in on a specific topic makes Sam have specialized knowledge on said topic, while not realizing how much he, in fact, knows about the topic.
For Sam this is all things Shire, but more specifically gardening and cooking. He takes a deep pride in his vast knowledge of gardening and cooking facts. We see this in small things like how he packs for his journey with Frodo. He packs things for cooking and brings herbs and spices from the Shire with him. Not only does he think they will need these items, but they are a form of self expression in what is important to him personally. In The Two Towers: Extended Edition, we see that Sam risks his life to save salt from the Shire. Although in the big scheme, such an item is not important, it is to him. This specific item has a great personal meaning for him.
Sam is also using Si being an expert on all things gardening. He even knows the specific plant Athelas, otherwise known as Kingsfoil. Something that only the Ranger, who has traveled far and wide, is aware of. The other Hobbits, despite their culture being into gardening, do not know of such a plant.
A common misconception of ISJs in general is that they take on social roles for the sake of society and their need to fit in it and get the job done. This way of thinking of ISJs is quite wrong and rings truer for EJs. Sam uses his Si for his interests and Fe to find the social role that best fits this interest. Hence, we have Sam the Gardner. He is so utterly proud of his position, not because of the way the position fits into the social system of the Shire (Fe), but because of his strong passion for gardening itself (Si). No where do we see this more evident than in the original texts by J.R.R. Tolkien, when he is the one who replants across middle earth. He regrows all of Middle Earth not because of some big picture, but simply and beautifully from his love of things that grow. He gets to actualize his gardening passion and he changed the whole of middle-earth for the better.
Si also gets a bad wrap for seeming old hat or conformist. However, neither of these are true statements about Si. ISJs like Sam are often quite whimsical and have a strong personal view of the world. The difference between an Si dominant and Fi/Ti/Ni dominants that associate that kind of uniqueness to themselves, is that SI dominants like Samwise don’t realize how individual their viewpoint is till they share it with others. This is evident when Gandalf the Grey passes away and they are in Lothlorien. Sam tries to recite a poem about Gandalf this great wizard who has been on many adventures, but what he remembers, what matters to him, are his fireworks. That memory held such a deep meaning to him. Gandalf is not a great and powerful wizard in Sam’s eyes, but the man who brought beautiful fireworks to his home.
Auxiliary Function, Extroverted Feeling, Fe: Extroverted Feeling is the part of Sam that many remember. It is the part of him that makes him people focused. However, unlike EFJs who are concerned with the whole of people, Sam is an ISFJ, which concerns itself with specific people who matter to him. We see this in his iconic relationship with Frodo.
Sam has a personal relationship with Frodo and that his where is caring and loyalty lies. He uses his Si to hone in on those he cares about and his Fe is what leads him to put his energy in outwardly caring for Frodo. His caring is shown through his actions and practical care, which comes from his Si. He makes sure that Frodo has his strength, that he is fed, that he isn’t carrying too much of the burden. He isn’t trying to understand Frodo with Ni on a psychological level, but making sure that all of Frodo’s needs are met.
The Si-Fe combo creates a fierce ally in Sam for Frodo. It is why ISFJs are referred to as ‘The Defender.’ Sam isn’t thinking of Middle-Earth or the Fellowship in a dominant Fe sense of keeping the social harmony. He is focused on helping Frodo specifically and defending Frodo from anyone who would do him wrong. He protects Frodo from others in the Fellowship. But we see it most in his disregard for everyone else other than Frodo when he swims out to the boat when Frodo leaves the Fellowship. He will always defend and help Frodo in any way he can. Even when Frodo leaves Sam behind, Sam follows Frodo to make sure he is safe.
Fe also means that Sam needs to feel needed. Hence why, despite still following Frodo after being left behind, we see such heart break when Frodo tells Sam to go home. “I don’t need you anymore,” Frodo says to him in The Return of the King. That is the line that cuts at Sam more than anything else.
Tertiary Function, Introverted Thinking, Ti: This function and Fi both help maintain unconditional human values despite a lack of immediate gratification in upholding and maintaining said values. In an introvert like Sam though, using this function too much and ignoring his Fe can create quite a problem for him. We see this most in his handling of Frodo and Gollum’s relationship. He isn’t using his Fe enough to read Frodo’s attachment to Golllum. He can’t get outside of his own head and even fathom why Frodo is bringing this creature along. So by skipping Fe, his Si is fed by his Ti.
Without seeing outside of himself, Sam is then convinced by his Ti that he is the only sane, logical, and rational person in the group. He must maintain the rationality and prove Gollum’s inevitable betrayal. However, this approach back fires in causing distrust between him and Frodo. He spent so much time trying to prove in a logical manner that Gollum was a sneak, that he missed the reasons why Frodo had Gollum around and was unable to convince Frodo of Gollum’s duplicity.
Inferior Function, Extroverted Intuition, Ne: Extroverted Intuition is in direct conflict with Sam’s Introverted Sensing. His Si derives consistent patterns of inner meaning from his immediate surface impressions, while Ne suggests that these impressions are part of an external meaning outside of himself that are ever changing. This is what makes Sam and other ISJs cautious of change that occurs outside of themselves. Without using Fe enough, Sam has a hard time consolidating his Si-Ne impressions and becomes extra weary and cautious.
We see this when they bring The Ring to Rivendell. He wants him and Frodo to go back to the Shire. They did what they set out to do, what more do these people and the world want from them? He feels that these changes, this bigger world and their new roles in it, are compromising his sense of self. He doesn’t have a certainty of who he is in this new world.
However, we do see Sam consolidate these opposing functions quite well when he is forced to use his Fe. Frodo signs up to be the ring bearer, and Sam’s Fe–his need to help Frodo–trumps his fear and caution of his inferior function. His place is to help and protect Frodo, and he can face whatever changes come his way. With Fe Sam isn’t afraid of his Ne and can embrace it and use it as a strength. He can explore the world, see the Oliphants, and appreciate the world outside of himself with his Fe guiding him.