CURIOSITY. That's the word I think of first in connection with Type Five. Fives have a strong need to understand their world. Ferreting out answers to all their questions about the hows and whys of life is the activity that consumes them. They are excellent and keen observers. Being one of the withdrawn types (along with Four and Nine), they have some tendency towards introversion and solitary habits, primarily to support their need to study things all the time. Depending on their instinctual stacking as well as how cool and fun they are perceived as being by others, they might be loners locked perpetually in their own rooms with their books or computers, or successful and well-received in their social circle, but the "nerd with glasses," "geek" or "techie person" is their stereotypical image. It's no surprise that they are in the "Head" or "Thinking" center (along with Types Six and Seven).
The core issues of the Thinking Center are with fear and anxiety, and each Thinking Center type deals with their fears and anxieties in a different way. Type Sevens run away from their anxieties and try to pretend they don't exist. Type Sixes for the most part acknowledge their fears and try to take steps to protect themselves and their loved ones from the perceived dangers. Type Fives (one of the rarest types on the Enneagram) face their fears head-on, and in fact feel the need to extensively study and examine them -- to understand how scary things make them feel and why, and/or to "shine light into dark spaces" by understanding the scary thing itself inside and out so that it will become well-known and consequently perhaps no longer quite as scary -- and they can actually become gruesomely fascinated with genres like horror because of this drive of theirs. (Not that they necessarily will, but they can.)
As one of the "level-headed" Enneagram types (along with One and Three), they have a definite tendency toward the (objective, logical) Thinking preference in Myers-Briggs. They certainly experience emotion -- in fact, are said to be quite sensitive -- but most Fives don't allow emotion to take over their decision-making the majority of the time. Nor are they in the habit of seeking others' advice very often, as many Sixes often do. Fives trust their own ability to come up with the right answers to any questions they may have, through study and experimentation of their own and/or through looking up the results of others' scientific study and experimentation. Fives make expert scientists and researchers, are often loners and try their best to be self-reliant.
Fives' experience of life involves the sense of never having enough time, energy, money, etc. to do what they strongly feel they need to do, so as a result, they zealously hoard whatever they have. Their time alone for study and thought is immeasurably precious to them, and trying to barge in on them or insist they break out of their shell and join the group will only result in their feeling desperate to escape from you. A task that would seem easy and quick to others might to Fives seem liable to sap far more valuable time and energy from them than they can afford to expend, so they'll likely decline to accept the responsibility if they can possibly get out of it. Since money represents hours of work and Fives are so reluctant to do any work not of their own choosing (and plus they have a tendency to live in their heads amid their interesting thoughts and neglect other bodily needs somewhat), you can see how they'd develop the desire to minimize spending, even on what others would consider bodily necessities, what to speak of anything more frivolous. In spite of the reckless neglect they may sometimes inflict on their own health when absorbed in a long stint of research or working on some project, Fives belong to the "Self-Preservation" triad (2, 5 and 8). Although there are several ways these "self-pres" instincts could manifest in their nature, one possibility is that the Five might be innately conscious of and concerned about the necessities of physical survival, wishing to know the practicalities of how these will be provided. These innate self-pres concerns plus reluctance to have their treasured freedom to explore, learn and think cut into by too many undesired obligations (either at an ordinary job, or in a scenario where they're financially supported by/indebted to others and feeling an internal or external pressure to reciprocate in some way because of that) can result in a tension/anxiety that causes them to minimize their physical needs down to the bare minimum and hoard every penny they possibly can against future need.
Fives are one of the most independent types on the Enneagram. First of all they want to figure out for themselves exactly how their cherished projects ought to be accomplished, and then they tend to feel strongly about the conclusions that their years of research have led them to. Compromising with others wouldn't be very appealing to them. If they were going to work with anyone else, the Five would do best in positions like expert adviser or leader. Fives aren't pawns, they're masterminds. Another aspect of the 2-5-8 triad is that all these types, whether they know it or not, have some desire for power. However, although I wouldn't say it could never happen, on the whole I would not expect Fives to be excessively overbearing leaders. They really shine when others flock to them of their own accord due to being inspired by the Five's clear vision, and support the Five willingly. If that's not the case, the Five is happy to splinter off and work alone. Their motto in relationships is "I won't expect much of you, so you shouldn't expect much of me."
If a Five has tried to tackle a problem in the characteristically 5ish way -- i.e. analyzing, dissecting, trying to understand it and arrive at the best plan of action -- and this has failed to eliminate the problem, the Five will then "go to Seven", i.e. conclude "OK, if I can't get rid of this problem yet, then let me take my mind off it and just have fun! Yeah! Party time!" Stressed Fives exhibiting the qualities of unhealthy Sevens may be unusually social, not feeling as much need for alone time as they normally do; be more scatter-brained, distractible, impulsive, undisciplined and frenetic / lose their accustomed clarity, patience, concentration, discipline and diligence; and possibly suffer from an unhealthy optimism that is out of touch with reality (very unusual for them because normally they're objective, scientific realists -- due to their tendency to focus on fears/anxieties/negativities rather than gloss them over or shy away, they can even become skeptical cynics in some cases). When exceptionally healthy, on the other hand, Fives will begin to exhibit the qualities of healthy Eights -- i.e., they will finally get out of the stage where they're always studying, planning and preparing for life, and actually step into the life they've always wanted to live, wherein they feel empowered, confident, energized, sure of themselves, and ready to take the helm in a worthy project or cause and help lead the way to a better future for all.
The wing types:
Fives with 4 as their stronger wing are more integrated with their emotions (and thus more spontaneous and natural in expressing them) than Fives with a more prominent 6-wing. The latter tend to separate themselves more from their emotions, being aware of them but studying them as something different and separate from themselves, and the result can be a highly poker-faced, maybe almost robotic-seeming person in extreme cases. 5w4s can be quite passionate in their emotions and behaviors at times. Another big distinction is that, Type Four being the classic introvert as well as proud to be "different/unusual", 5w4s tend to direct their 5ish drive to study and understand towards themselves, their inner worlds, and the more unseen, impenetrable, vague and unfathomable realms of reality. Willingness to accept highly theoretical/speculative systems of understanding -- a leaning towards more intuitive, esoteric, occult or "alternative" sciences -- and attraction to things like philosophy and very deep questions of why things are the way they are, which you can think about with your mind but not so much observe with your physical senses, tend to be attributes of the 5w4. In comparison, 5w6s are more focused on the natural, observable world that surrounds them and technical questions about how it all works. Empiricism, skepticism, and the stereotypically strict "just the facts" scientist personality would fit more with 5w6 than 5w4. This is not at all to say that a 5w4 can't be interested in natural science nor a 5w6 in philosophy; any Type 5 can become interested in any system of knowledge. But those general tendencies have been seen. Also, due to the 5w6's attraction to our natural world, this type often feels happier with realism in art and literature. In fantasy or science fiction, the 5w6 may prefer to see the imaginary worlds follow laws of nature that are more or less similar to this world's. The 5w4, on the other hand, often gets a kick out of completely bizarre, surreal, and mind-boggling ideas, scenarios, situations or landscapes. The 5w4 is also the one more likely to become obsessed with horror.
Since Type Six is very social, 5w6s may tend to be
friendlier towards others than 5w4, more anxious to fit in with and use their talents for the benefit of society somehow if
possible -- although again, this is not at all to say that a 5w4 couldn't want to do that too, nor that a 5w6 would never be a misanthropic loner. And one last point (though, yet again, none of this is set in stone) is that since Type Four is usually more spontaneous and impulsive whereas Type Six is considered a "compliant" (i.e., hardworking and responsible) type, 5w4s might lean somewhat toward a Perceiving preference in Myers-Briggs (spontaneity) whereas 5w6s might lean more towards Judging (order and organization).