While their mechanical tendencies can make them appear simple at a glance, ISTPs are actually quite enigmatic. Friendly but very private, calm but suddenly spontaneous, extremely curious but unable to stay focused on formal studies, ISTP personalities can be a challenge to predict, even by their friends and loved ones. ISTPs can seem very loyal and steady for a while, but they tend to build up a store of impulsive energy that explodes without warning, taking their interests in bold new directions.

ISTPs have a particular difficulty in predicting emotions, but this is just a natural extension of their fairness, given how difficult it is to gauge ISTPs' emotions and motivations. However, their tendency to explore their relationships through their actions rather than through empathy can lead to some very frustrating situations. People with the ISTP personality type struggle with boundaries and guidelines, preferring the freedom to move about and color outside the lines if they need to.