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.)
Tertiary and inferior Fi also sometimes lead TJs to view large numbers of people as "troglodytes": soulless or stupid creatures whose rotten situations in life derive only from their own intrinsic rottenness-of-soul. To take a comic example, Lex Luthor's lamentation in Superman, "Why is the world's greatest criminal genius surrounded by nincompoops?"
Perhaps the most typical manifestation of tertiary and inferior Fi is an attitude of psychologizing other people: a sort of pseudo-empathy in which one explains other people's behavior in terms of pitiful needs and psychological flaws that anyone would be ashamed to have. "Notice the defensiveness. He clings desperately to his ideas. Such weakness." (Nearly all psychological theories offer plenty of ammo for psychologizing, including Lenore Thomson's ideas.) Where developed Fi leads you to find something in your own soul in terms of which to truly understand someone else and see things their way, tertiary and inferior Fi typically lead you to find something in your own soul that you despise, in terms of which you can "explain" them and justify putting them down.
Naturally, you can see plenty of dominant-style Fi in ETJs, secondary-style Fi in IFPs, and so on--even inferior-style Fi in IFPs.