I've recently been thinking about myself a lot, and looked some things up.
Now, I want to preface this with a disclaimer of sorts. I do not believe in the Myers Briggs personality types as a 100% foolproof fact. I think of the types as a guideline for understanding people. It just so happens, that I have one of those extra weird types, and that even after critical examination of the stereotypes and my own personality, more of those two things align than I ever really thought.
The INFP personality types, is an idealist. Someone who functions terribly in the real world. I have found that a lot of things can be said about the INFP type, and one of the biggest things, is that they are filled with contradictions. They love people, but are reclusive. They're very ambitious, but extremely lazy. They want to feel extremely close and intimate with another person, but can't open up about themselves.
The big thing here, is that contradiction part. They are both ends of the spectrum. They want this one thing, or feel this one way, and also want the exact opposite thing, and feel the complete opposing feeling. INFPs are very lonely, even when they have all the friends they could ever need reaching out to them trying to help. This is because those friends aren't real friends. They're colleagues or acquaintances.
Real friends to the INFP are so close to them, that the INFP can open their shell for. These true friends learn all sorts of things about INFPs that they would normally hide from the rest of the world. However, all INFPs have been hurt. They've all opened themselves up to others, and been betrayed. Someone has hurt them and lost the trust of that INFP. So they are extra guarded. But if you can prove yourself, and be a real friend, someone the INFP can actually believe in and trust, you're in for life, or until you commit a massive betrayal.
INFPs aren't like most other people in that sense. You may think that you're friends with them, maybe even close friends. But if you're a real friend from the INFPs perspective, you're a friend for life. They'll move mountains to help you, and part oceans through sheer force of will. Because you are a real friend of theirs. Not just someone that they say, "Oh that's my buddy Jim. I've known him for a few months now." An INFP says "Oh that's my friend Jim. I helped him move a few days ago, and we're going to start painting his new house in a few more days. I've known him for a couple of years."
When you actually get in as a real friend with an INFP, their personality might seem to shift drastically. Because they give you a lot of trust. And that trust is not easily broken. A lot of INFPs can tell when you're lying. It's something they can tell, because they do it all the time. Not outright lies, but their personality they display to the world is usually fabricated. Specifically for the purpose of being around people that they don't know well or trust.
Almost any lie you tell an INFP is spotted, and remembered. Most INFPs have a really good memory for that type of thing. However, they're not going to tell you they know. An INFP almost always knows the lie, even if they don't know the truth. Because of this, INFPs don't like it when you lie. But if you tell them that you don't want to say the truth, they'll be fine with that. Because it means you aren't pretending, you're just waiting for the right moment. Something that all INFPs understand very well.
Another thing to keep in mind about interacting with an INFP, is that you're competing for their attention, all the time. If the INFP values you in any way, you're competing far less, but you're still competing. The other competitor is the INFPs own brain. You are competing against whatever fantastical ideas or impossible thoughts are currently in their head. So to really have their attention all to yourself, you have to be so foreign and strange to them that you take their attention.
Now, that's not to say you have to be the most interesting person on the planet. Far from it. You just have to be different enough, in enough ways, from the INFP that they want to get closer to you and understand you. Something that not a lot of people can really do. Because the INFP knows about the public lexicon idea of the "regular person." A nine to five job, partner at home, a modest size living space. That isn't a very interesting person to the INFP. Unless you're smart, or humourous, or knowledgeable about a very niche subject, or can relate to an interest of the INFPs.
And lastly, you need to be understanding of the INFP. They may hide things from you, but usually because they are afraid of ridicule. They may disappear for stretches of time, but it's not because of you. They just have an urge to be somewhere that doesn't exist, so they leave to find it in their head. Trust that they'll come back, and you will see them again. And for the love of their sanity, don't be angry with them. They're trying their best to function in the real world, but the worlds that are inside their own head call out to them. They try and try to resist living just in their head, but it doesn't always work like that. So when they disappear and reappear, don't be angry. Welcome them back with open arms, and let them re-adapt to being near real people.
As one semi-faceless INFP to all the people in the world, don't be harsh to us. We're trying as best we can, but the worlds inside our head are so much kinder and safer. We want to know real people, but you have to let us try our best and not be harsh when we fail. Just give us the nudge we need to get out of our heads and back into the conversation.