I am an ISFJ type which means I am introverted, sensing, feeling, and judging.
ISFJs are characterized above all by their desire to serve others, their "need to be needed." In extreme cases, this need is so strong that standard give-and-take relationships are deeply unsatisfying to them; however, most ISFJs find more than enough with which to occupy themselves within the framework of a normal life. (Since ISFJs, like all SJs, are very much bound by the prevailing social conventions, their form of "service" is likely to exclude any elements of moral or political controversy; they specialize in the local, the personal, and the practical.)
ISFJs are often unappreciated, at work, home, and play. Ironically, because they prove over and over that they can be relied on for their loyalty and unstinting, high-quality work, those around them often take them for granted--even take advantage of them. Admittedly, the problem is sometimes aggravated by the ISFJs themselves; for instance, they are notoriously bad at delegating ("If you want it done right, do it yourself"). And although they're hurt by being treated like doormats, they are often unwilling to toot their own horns about their accomplishments because they feel that although they deserve more credit than they're getting, it's somehow wrong to want any sort of reward for doing work (which is supposed to be a virtue in itself). (And as low-profile Is, their actions don't call attention to themselves as with charismatic Es.) Because of all of this, ISFJs are often overworked, and as a result may suffer from psychosomatic illnesses.
My opposite is ENTP which is extroverted, intuition, thinking, and perceiving.
ENTPs are usually verbally as well as cerebrally quick, and generally love to argue--both for its own sake, and to show off their debating skills. ENTPs tend to have a perverse sense of humor as well, and enjoy playing devil's advocate. This sometimes confuses, even angers, those who don't understand or accept the concept of argument as a sport.
ENTPs are as innovative and ingenious at problem-solving as they are at verbal gymnastics; on occasion, however, they manage to outsmart themselves. ENTPs can be prone to "sharp practice" – especially cutting corners without regard to the rules if it's expedient – or, their juggling acts may simply be so over-ambitious they collapse.
Both at work and at home, ENTPs are very fond of "toys" -- physical or intellectual, the more sophisticated the better. Once these have been "solved" or become too familiar, however, they’ll be replaced with new ones. ENTPs are basically optimists, but in spite of this (perhaps because of it?), they can become petulant about small setbacks and inconveniences. (Major setbacks they regard as challenges, and tackle with determination.) ENTPs have little patience with those they consider wrongheaded or unintelligent, and show little restraint in demonstrating this. In general, however, they are genial, even charming, when not being harassed by life.