As a Dominant Function, Fi leads IFPs to live a life based on empathy and harmony between self and others--and/or to see life as a never-ending conflict between souls that are intrinsically different and opposed. ISFPs typically seek out a space in which they can be completely and spontaneously themselves, following their artistic impulses without regard to social expectation or definition of any sort. Some do their best to live life as a soap opera: creating and living out intense drama wherever they go. INFPs typically seek to understand the world in terms of drama, emotion, and people seeking their own unique callings (perhaps Garrison Keillor is a good example of that). Some, like John Gray, attempt to help others understand each other through empathy with each other's differences, and thereby find peace and synergy.
Developed Fi naturally leads people to favor mercy or forgiveness for people who have done heinous acts--anything from theft to murder to genocide--acts that, under the ordinary laws that make a society manageable (see Extraverted Thinking), would usually merit their imprisonment or execution. From a developed Fi perspective, the criminal is still a living soul, still unique and precious despite whatever he may have done. If we walked in his moccasins for a while, maybe we could see it his way. Without condoning his crimes, maybe we could see how we ourselves could have done the same things under similar circumstances. This use of empathy as one's ultimate anchor of orientation leads to a resolute non-judgementalness. First empathize--find something in your own heart that lets you see how someone could feel and act the way he did--and then you will probably find that you no longer feel hatred or a desire for retribution.
As a Secondary Function, Fi typically leads EFPs to tune into the unmet needs and callings of others--as an avenue to making a sale, as a way to intuit what would entertain people, as a channel to political gain by demonstrating that you understand people's pain (e.g. Bill Clinton), as a way to chart a course through life based on a calling felt to be unique to them. Sometimes it leads them to sense a higher calling to answer to, a sense that their actions have cosmic meaning by virtue of how they aid or hinder life.
As a Tertiary Function, Fi typically leads ITJs to retreat into solitary actions that have no constructive worldly effect but are aimed at providing a justification for calling themselves good people. Another example is obsession with the purity of one's soul. For example, being a vegetarian while working at Taco Bell--not out of any great love for animals (the person might hardly know anything about what cows are like), but to be able to say, "Well, at least I never ate any animals." Or engaging in pointless acts of honor, like maintaining super-self-control or "doing one's duty" or going down with the ship. Nothing is gained by going down with the ship; it's a hyper-introverted act aimed at providing a rationalization for one's goodness without regard to real-world consequences. Nearly all of these tertiary-Fi acts involve refraining from action viewed as unethical rather than taking positive action that would accomplish something. They're a retreat from the world--or rather, a rationalization for disregarding worldly matters.
As an Inferior Function, Fi typically leads ETJs to acts of self-destructive hedonism, creation of opera-like drama in their lives and the lives of those around them, obsession with "integrity" (like going down with the ship), instant and irresponsible abandonment of anything they don't like (the opposite of going down with the ship), and bizarre solitary acts of atonement for the harms they've done to others. Sometimes inferior-Fi leads ETJs to preach and even practice a sort of hyper-selfishness, e.g. Ayn Rand and the Landmark Forum. "I'm doing fine, so why should I give a damn about you?" (Very different from highly developed Fi, which leads you to see all people as connected and the highest joy of life as the experience of that connection.)