1. Fe – extroverted Feeling
Fe is the FeSi’s primary function and is what they use to communicate with the world. It is also how the world communicates back to them. Fe is not about emotions, but the “gut instincts” they might have about a person or situation. This function is focused outwardly and is primarily motivated and energized by the presence of other awesome people. Because Fe is first, all the other functions “serve” it.

2. Si – introverted Sensing
While Fe gathers information about people, Si is running internally in the background to keep track of this information in an organized fashion—like a filing cabinet or a very organized library. Si helps FeSi’s remember data that is important to them and helps them to determine if things are “right” or “wrong” based on the data that is collected by Fe.

3. Ne – extroverted iNtuition
Ne supports Fe as it helps fuel the FeSi’s instincts about the world around them. It helps them navigate unfamiliar situations and see potential in people. Ne also helps keep their Si in check, so that when they use Si they don’t become too set in their ways, which can isolate some people.

4. Ti – introverted Thinking
Ti is the FeSi’s last function, so it can be their Achilles heel. Their Ti, in tandem with Si, helps them examine and analyze information that Fe collects. Ti helps them determine if their ideas and opinions stand up to scrutiny. However, because Ti is their weakest link, they might have trouble when asked to analyze complex theoretical problems in their head—i.e. intricate math equations.