The ISTP will be full-on, or full off - they don’t do shades of grey. The ISTP personality type moves seamlessly from quiet bystander to active participant and leader in one fell swoop, then back again to invisible, apparently disinterested introvert. They are at their best in times of crisis and challenge, but will have little appetite for follow-through, as they will be waiting for the next challenge. Independent and self-contained the ISTP, although not unfriendly, will be difficult to get to know as they tend to reveal only what they choose to and that is over time when they are ready.
The ISTP is one of the most complex character types either in the thick of the action, leading and solving problems, or with nothing to say. The issue is they only say what needs to be said, they are economic in the extreme. This is because ISTPs are driven purely by challenge and this will determine how involved they want to be, how big is the challenge? They are at their best in times of crisis as they need very little preparation and able to cut to the chase with no preamble or discussion with others, spontaneously jumping in to solve problems or deal with crises often surprising those who had seen them as on the periphery of things. However, once the task is finished or problem solved, they will be looking for the next big thing to throw themselves into.
The ISTP is self-sufficient and very independent, only really happy when undertaking some risky or interesting activity. Direct to the point of abruptness and tending at times to tread on toes, the ISTP tends to speak literally showing little concern for the impact, and they display coolness under pressure which helps get things fixed but which may not endear them to those around them, (even those for whom they’ve fixed something). They are not unfriendly individuals but ultimately the ISTP wants to be left alone to live their lives and do their jobs the way they see fit, rarely trying to control others and expecting others not to try to control them. But in a crisis, or when the situation needs in-depth understanding, the ISTP will thrive, at least until the crisis is over. Once they are clear on what needs to be done, they will be difficult to budge and will potentially move too quickly without thinking through all the implications as they just love the thrill of action. The switch may appear as from someone who is almost exclusively listening to someone who just doesn't listen. The ISTP dislikes theories and complexities, preferring facts and data which will help get the job done in the quickest possible time and with the minimum amount of effort.
The ISTP is the ultimate trouble-shooter, able to unpick and understand how things fit together and then fix them. The ISTP doesn’t follow social rules, nor do they need to engage fully with others and this can give them a distant, aloof persona to others who often don’t quite know where they stand. Practical, resourceful, adaptable pragmatists, ISTPs have excellent powers of observation, a capacity for understanding how anything works, displaying logical, detached analysis. The ISTP has a great ability to analyse facts and store data. This is all internalised, stored in the grey filing cabinets in the brain until called for. Then, when someone argues with the ISTP, the facts, data, empirical evidence, knowledge are brought quickly to bear to quash the argument, quickly and finally. The independent streak in the ISTP means that they will usually display confidence in their own abilities but means they may not bring others into the decision-making process. They are quick and economic and so their desire to get a result in the minimum amount of time and fuss means they may overlook the personal touch and make them fail to see the 'bigger picture,' and so, by quickly solving a problem, they may create another.
The ISTP is very difficult to read. Their areas of interest tend to be mechanical and physical but unlike most SPs they don’t need constant action, they actually lie low, storing all the data saving their energy until a project or an adventure they consider worth their time and effort arises, and then they launch themselves in completely. They work in short bursts of incredible energy, loving fixing and sorting, especially factual mechanical issues but, when it's over it's over, no reflection, no discussion, no hanging in there, they've gone.