The quest for peace is the defining characteristic of Type Nine. As one of the three types that inherently contain the social instinct (3, 6 and 9), awareness of discontent or suffering in anyone or anything tends to disturb the Nine until the problems have been resolved and peace restored. This concern and sensitivity toward others leads to the Nine's classification amongst the relationship-oriented types (2, 6 and 9). As the core members of the "gut" or "instinctual" center (8, 9 and 1), Nines are possessed of an innate, effortless awareness of certain things such as the moods and nonverbal cues of people around them, and may instinctively know what to say and do in order to achieve the effects they're looking for, especially on people they know well. Specifically, when they operate in this role, their goal is normally to maintain a balancing act, delicately sustaining the good mood of everyone present. Nines find it so easy to understand and sympathize with everyone else's points of view that they can often (not always!) find it difficult to figure out what they themselves feel about any particular issue. Listening to one side may convince them that that side is right, but after listening to the other side for a while, their opinion may sway over in that direction again. Being one of the positive-outlook types (2, 7 and 9), plus being easygoing, sympathetic toward others and relationship-oriented, Nines are drawn to appreciating the good qualities of others, choosing to overlook the bad, and giving everyone the benefit of the doubt. Seeing all sides of the argument and seeing others' positive qualities as they do, they tend to be very good-hearted, fair and impartial. It's no surprise that with this natural empathy that they possess toward one and all, Nines hate conflict, and their personality type is often referred to as "the peacemaker" because of the lengths many of them would go to to establish harmony. I've seen it stated in completely simple, straightforward, matter-of-fact terms that "Nines are likable", whereas I haven't seen this statement made so unequivocally about any of the other types on the Enneagram. But this really is no surprise either, since Nines usually make it their business to adjust themselves to the needs and desires of others, to be the unassuming and undemanding supportive friend and fill whatever role is required of them in order for peace to be maintained. Unlike Twos, who crave the loving attention of others for themselves but try to earn it by first focusing on those others and showering them with every kind of service (and who thus develop the attitude that they are highly deserving of reciprocation), Nines are naturally humble and simple; if they don't get much in the way of recognition or reward for their efforts, they're genuinely fine with that. They might bask happily in the appreciation of others if it is freely offered, but they're quite comfortable outside the spotlight, and the services they perform are done for the sake of their intrinsic value, with no strings attached. Unlike Sixes, instead of complaining about every small grievance they must endure in life, Nines can easily tolerate most inconveniences with a mild, pleasant disposition. They don't ordinarily pollute the ears of others with grating tirades or unkind gossip, but rather tend to go (by and large) by the motto "if you can't say something nice, don't say anything at all." Most people do indeed find such traits appealing and attractive, or at least non-disturbing, so Nines don't tend to earn themselves many enemies.
However, aside from mediating differences and solving problems outside of themselves, there is another strategy often employed by Nines for maintaining their own peace of mind: a strategy which may be good in moderation but can definitely be taken too far and become an unhealthy thing. It is the choice to take shelter behind a "wall" or within a "shell" -- a resolution to ignore disturbing elements either outside the Nine or within his or her own mind or body. Fully aware that the displeasing element exists and yet disinclined to deal with it, the Nine will deliberately look the other way in a bid to maintain his or her internal calm. If carried too far, this descent into deliberate ignorance can lead to a sort of heaviness or immovability; a habitual inertia. I myself have experienced the debilitating results of letting this tendency take over my life; it became difficult for me to accomplish anything very significant or useful due to employing my skills at ignoring and tolerating in the wrong way. Temporary inaction and stillness in order to peacefully contemplate, meditate, or commune with nature may be healthy things for other personality types to practice (notably Type Six, which is the "stress point" for Type Nine, or the type that Nine "goes to" when disintegrating), but for Nines, undisciplined forms of these practices come so naturally that Nines should be encouraged in the opposite direction in order to achieve balance -- towards the healthy aspects of Type Three, namely self-motivation, goal-setting, and the active making and executing of plans.
Retreating within their wall of ignorance is the method of withdrawal that Nines use (they are one of the three withdrawn types -- 4, 5 and 9), and since it enables them to numb themselves so that they can endure any mental or emotional pain, it also enables them to be very stubborn and immovable in case someone wants something from them that they are unwilling to give. Thus, even though Nines are generally accommodating of others and appear very gentle, pliable and soft-natured (they tend to have a hard time telling people "no"; a noncommittal "maybe" or even an insincere "yes" with a lack of follow-through are more to be expected from them), they are actually very tough and strong inside; if they don't want to do something, they know very well that no one can make them. This "checked-out" uninvolvement and recalcitrant stubbornness can, indeed, be distasteful to others, especially when carried to an extreme (it may be more likely in Nines whose instinctual stacking is self-preservation-first, although any Nines can let themselves be overtaken by it -- I'm a social-first, self-pres-LAST Nine who is very much guilty of that crime), so Nines aren't necessarily always likable to everybody.
By the way, speaking of instinctual stacking, I wish to emphasize that not all Nines are involved in or even concerned about social issues like world peace; "live and let live" is a motto that tends to apply to Nines of any instinctual stacking, so surely if asked for their opinion, any Nine would be in favor of peaceful conditions in the nation or the world, but there are plenty of them who don't bother to lift a finger to try and make it happen. That would be the case when numbness/inertia/ignorance are more prominent in the Nine's chosen nature. "Eh, I can't change it, so why should I care? Let me just hang out on the couch watching TV or whatever else I like to do for fun, and let other people work it out for themselves." Self-pres-first Nines might be more likely to think like that.
Another thing that certain people may find annoying about Nines is that they tend toward Perceiving in Myers-Briggs, with all the traits that entails: spaced-out, daydreamy, noncommittal, chronically late, and not too particular about the appearance of their own bodies or homes, i.e. a bit frumpy and messy may be OK with them. This doesn't apply to all Nines, but it is a tendency that may be seen in them to one degree or another.
As gut-center members (8, 9, 1), their innermost issues are with rage, which is deeply suppressed by them most of the time. Many Nines may not think of themselves as having a temper at all; but when something finally causes them to lose it, they can be explosive. When Nines have been accustomed to numbing or suppressing their feelings for a long time and are just beginning to let themselves come out of that state, in many cases the first thing they're able to feel is anger, sometimes surprisingly powerful anger. If vented in a healthy manner, it will soon simmer down to manageable levels and eventually be replaced by the forgiveness and calm that Nines are more accustomed to from themselves; but in that case the forgiveness and calm will be more healthy and genuine than ever before, shining out from their very souls.
The wing types:
Nines with an 8-wing are called "The Referee" by Riso and Hudson. They are the kind of people who can stand up, raise their voices and say "Hey, everybody! Here's what we've got to do! You do this, and you do that. I know just how to keep everyone happy, chilled-out and having fun, and I'm not afraid to assert myself to make sure that's exactly what happens!"
Nines with a 1-wing are idealistic, moralistic, nit-picky about small details, often model children, usually very accepting of and loyal to authority. They may be more dreamy and less practical than the other wing type.