So, I've been thinking a lot lately about Fi, and how it's so often associated with morality, despite the fact that at the most basic level, it's just about the bonds between people.
What I realized is that Fi does have to do with morality, in a certain sense. This is because, since Fi focuses on the bonds between people, it also focuses on what will help and what will harm those bonds on a far deeper level than any of the other functions. This is the connection to morality. Specifically, I think a connection can be drawn between Fi and deontological ethics. Deontological ethics focuses on what should and should not be done to another person, i.e., bonds of obligation. This is precisely what Fi focuses on. Fi is not so much about making moral judgments about other people, and when paired with Ne, it actively avoids assuming that a person will always behave in a certain way because "that's the kind of person they are." Rather, Fi is concerned with the bonds of obligations of certain types of relationships. Fi is the voice that cries, "you can't do that to another human being," focusing on the obligation one member of the human race has to another. To do harm to another human being is to harm the implicit bond that exists between human beings. It is the voice that says "a husband should behave in a certain way towards a wife," and this assumption has its ultimate roots in an apprehension of what will help the bond and what will hurt the bond.
This clears up a quandry I was in about determining whether a given judgment is Fi or Ti related. Both Fi and Ti are inclined to make generalized prescriptions about what should or should not be done in general. Both Fi and Ti make "rules". But Ti rules are rooted in avoiding logical contradictions between givens: given that a king is greater than a subject, and given that a subject correcting a king implies the reverse, subjects should not correct kings. That's an extreme example, but you get the point. Fi rules, as I have said, are rooted in information about what will help or harm a bond between a group or pair of individuals: since making jokes about weight will hurt the feelings of an overweight friend, one should not make jokes about weight, especially around that overweight friend.
Hurting someone's feelings is something that Fi types try to avoid, for two reasons: first, because the attention to the bonds between people gives Fi types great capacity for empathy, and secondly because feelings in the sense of subjective sentiments from one person about another are a type of bond, or emotional relationship, between two individuals, something of which Fi types are extremely aware.
Also, note that an Fi type can use their understanding of relationships to hurt as well as to help. An Fi-ego can deliberately take actions that they know will hurt or sever the bond between herself and another person. But they usually feel bad afterwords, especially deltas (ESIs can be a little more ruthless, as can SEEs).
So, those are my thoughts. Opinions, questions, disagreements?