In this part I'll be talking about positions of the functions, you might have figured out which functions you use the most after the last part?

How does NeTiFeSi
Turn into ENTP?

As I've said before, each type has 4 functions in its stack and the other 4 functions as their shadow functions, which I'll be talking briefly about in my next post. In today's post, I'll focus on the main stack.
Let's look at the stack for ENTP:
Ne - dominant
Ti - auxiliary
Fe - tertiary
Si - inferior

Ni - opposing
Te - critical parent
Fi - trickster
Se - demon

So what do the positions mean and how do they define your personality type?

Dominant function:
The dominant function is sometimes called "hero." That's because your dominant function is usually how you "save the day."
This is your strongest/most developed function that you're most comfortable using, you usually use it naturally without even noticing. You trust and rely on your dominant function the most - It's your comfort zone.
An extroverted type's dominant function is always an extroverted function like Ne or Te and introverts are always an introverted function like Fi or Si.

Example: ENxP's dominant function is Ne which means they see all the possibilities and patterns in the world. Ne is an extroverted function which makes ENxP an extroverted type and they tend to prefer interacting with the outer world. ENxPs can save the day by coming up with different solutions and ideas to solve a problem.

Auxiliary function:

This is your second strongest function and is also well-developed. The auxiliary function supports the dominant function and the auxiliary function together with the dominant function defines the majority of your personality.
The auxiliary function is also called "the parent" and that's because when you help other people you tend to start with your auxiliary function.
If your dominant function is introverted then your auxiliary has to be extroverted and the other way around, that's because they need to balance each other out.
Also if your dominant type is a perceiving type then your auxiliary has to be a judging type and the other way around, that's because we can't only take in information without making a decision or make decisions without any information to judge.

Example: An ENTP's auxiliary function is Ti (a judging type) which means they use Ti to make decisions based on the information Ne takes in.
Ti checks the validity of the ideas Ne comes up with and figures out how they would work.
When an ENTP helps someone they'll most likely use Ti so their solutions will be logical and the ENTP will focus on problem-solving rather than emotional comfort as a Fe auxiliary would.

Tertiary function:
The tertiary function is the third function in the stack and it will be well-developed in middle age. Until then you'll struggle with using it because it's underdeveloped. Using this function at a young age often leads to failure and awkward situations.
That doesn't mean you never use it the tertiary function is often called "the child" and it's the function we like to use sometimes to have fun. Someone once compared the function archetypes to passengers in a car; the dominant function is the parent that drives the most safely, the auxiliary function is a teen that recently learned driving and the tertiary function is the child in the back. The child would want to try driving the car for fun but would you let it?

Example: ExTP's tertiary function is Fe, in their younger year they tend to lack p awareness of other people's feelings and be insensitive towards them. But they can be more affected by others' opinions than they'd like because the Fe is still there.
As the Fe develops they'll develop people skills and understand others' emotions more easily, they'll be more socially aware, and can also use Fe for charm.

Inferior function:
The inferior function is the weakest and the least developed function in our stack. It is your weakness and the function that will take the longest and most practice to develop.
Sometimes called the lost/repressed function because it's the most unconscious one; it's the most difficult to access.
It's the function that you wish you could use but using it often leads to failure. A situation where you would have to only rely on your inferior function would most likely lead to difficulty and total failure.

Example:
ENxPs' inferior function is Si, which means they can often forget the details and physical needs while coming up with new possibilities. They may frequently forget to eat or shower and they'll lose their belongings often.

They can feel bored when being forced to pay attention to small detail or repeat to learn a skill because they skill novelty and new possibilities. They would have a hard time doing a job where they need to be precise or do the same thing over and over again.

:
The functions stack for each type:
ISTJ: Si>Te>Fi>Ne    ISFJ: Si>Fe>Ti>Ne
ESTJ: Te>Si>Ne>Fi    ESFJ: Fe>Si>Ne>Ti
INTJ: Ni>Te>Fi>Se   INFJ: Ni>Fe>Ti>Se
ENTJ: Te>Ni>Se>Fi    ENFJ: Fe>Ni>Se>Ti
INTP: Ti>Ne>Si>Fe    INFP: Fi>Ne>Si>Te
ENTP: Ne>Ti>Fe>Si    ENFP: Ne>Fi>Te>Si
ISTP: Ti>Se>Ni>Fe    ISFP: Fi>Se>Ni>Te
ESTP: Se>Ti>Fe>Ni    ESFP: Se>Fi>Te>Ni

Can you see any patterns?

"Rules" and patterns
There are some so-called rules for how a stack is built, you don't need to remember them all but it's good to know:
    - Introverted types have an introverted dom function and extroverted types have an extroverted dom function.
    - Every type leads with one judging and one perceiving function (For example TeSi = ESTJ)
    - Two introverted/extroverted functions can't be after each other like TiNiSeFe, the correct stack for these functions can be SeTiFeNi (ESTP)
    - Neither can two judging/perceiving functions follow each other like NeSiTeFi, the correct stack for these functions can be SiTeFiNe (ISTJ)
    - If you have an extroverted judging type (Te or Fe) as your dom or aux function then you are an xxxJ (judger), if you have an extroverted perceiving type (Se or Ne) then you are xxxP (perceiver)
    - Si dom/aux = xSxJ. Se dom/aux = xSxP. Ne dom/aux = xNxP. Ni dom/aux = xNxJ. Fe dom/aux = xFxJ. Fi dom/aux = xFxP. Te dom/aux = xTxJ. Ti dom/aux = xTxP.

Dom= Dominant Aux= Auxiliary Tert =Tertiary Inf= Inferior

I hope this part cleared up any misunderstandings, just comment if you have any questions!