Introverted iNtuition (Ni) is one of the most difficult functions to understand, and it also happens to be the dominant function of the INFJ (which explains why we are so hard to figure out, huh?).
Ni takes in information in an abstract way and often sees patterns and symbolism. One reason that Ni-users have a hard time explaining how Ni works is because they have a hard time understanding it themselves. This is because information comes to them seemingly “out of nowhere” and then they have to backtrack their thoughts and internally organize their processes to determine where the “Aha!” moment came from. It’s kind of like being given the answer to a riddle before you’ve heard the riddle itself. Even though INFJs prefer structure when it comes to Sensing activities, Ni doesn’t work well on a timetable. Ni is kind of the rebel child of the cognitive functions — it flows on its own and is hard to control. Another example of Ni not working well with a schedule would be if someone was given a guide explaining how a project should be done. The Ni-user would most likely develop their own, simpler process for how to get the project done and the step-by-step list wouldn’t seem necessary.
For INFJs, the Ni/Fe relationship is what causes us to “know” something about someone before they’ve told us. The Ni/Fe relationship can work to the INFJs advantage, but it can also cause conflict. Ni and Ti tend to work well together, taking in a big picture idea and breaking it down, analyzing it and coming up with some sort of solution. Ni/Se is an interesting and at times frustrating relationship. Se allows us to be aware of our surroundings, while Ni is often searching for a deeper meaning, which many times isn’t there. This is why other types (especially Sensors) can sometimes get annoyed or confused by our natural need to analyze or find meaning in simple things.