TP's: What is it like for you to use Fe in service to Ti?
Well, if I view functions as metaphors, with TI representing the logical, analytical side of me that strives for coherence, and Fe representing the emotional side of me that demands connection, engagement and security, I think I would describe it as such:
I strive to analyze the Fe, and look at what sets it off. I try to find patterns. What kind of thing upsets me and makes me lose control? What kind of thing makes me happy? What do I like about people? What do I hate? After a certain point, I can do some comparing, and compare my library of past reactions to the reactions and behavior of other individuals. I suppose I do not have an answer for situations that are not in my library, so I try and factor that in, too. For instance, if someone is an Iraq war vet, I do not really know entirely what they've been through, so I don't pretend to have answers when I do not.
The thing that a lot of INTPs don't realize is that you can predict this stuff. Emotions aren't totally mysterious things that have no explanation, and neither are human beings. Human beings merely appear mysterious and unknowable to other human beings (or INTPs) because nobody has complete information regarding another human being. Total knowledge of other humans is impossible, so one must make informed guesses while at the same time being prepared to accept information that contradicts these guesses. INTPs that have a strictly empirical approach to the world often find this difficult, because one perceives only the surface actions of others, and neglects the connecting threads that can help form a more coherent picture of an individual's personality. That is, if one believes that one should not engage in speculation, and rely only upon observable evidence, the INTP is suppressing their intuitive faculties and crippling themselves. Speculation can be incorrect or off-base, but it must be done, anyway. It is possible to do this while allowing room for error.
The benefits to this is that it enables the INTP to more smoothly navigate the interpersonal relationships that are an inescapable part of living. Ultimately, we can't go off and live as a desert hermit (I tried that; it was simply not viable or even possible). So, we have no choice but to try and understand other humans. In doing so, we can acquire compassion points.
I'm making this process sound a lot more mechanical than how I actually experience. The reality, as I experience it, is much more organic than mechanical. It appears mechanical because of the way I explain it.
I'm not sure how INFJs experience Fe fueled by Ti. Keep in mind that some people think I'm an INFP or INFJ ( not that I am concerned about such things any longer).