I've thought of the difference between the T and F functions can be (over)simplified to true/false versus good/bad. Logic versus evaluation.
Fi specifically has a worldview prioritizing a subjective viewpoint. Not what's best for me (although, when the dominant function Fi becomes ego serving, that can become true) but what's best for the individual. I think domFis live with their inner world so loud and so unignorable, they give a lot of heavy consideration on how actions affect themselves and, hopefully, others. An ego-serving Fi will not use Pe to add other pieces of information about other people and use only the values they have set for themselves. A more conscious individual will use what they know from exploring themselves so thoroughly, plus what they can gather from external clues, to gain a better understanding of how the inner life of individuals works.
Not that a domFi has to be an upstanding moral citizen, or even focus any energy to helping people, but most domFis tend to agree it feels bad to hurt others, and it feels bad to be hurt. It's just a natural conclusion to a fair number of domFis.
I really do think that there is a very big lack of introverted feeling descriptions that accurately convey what Fi is and does, instead focusing far too much on painting some crazy saintly picture hardly anyone lives up to, or some crazy emotional wreck that underplays why Fi feels so strongly.