Pam Beesly is known for her shyness, sensitivity, and artistic inclinations. Over the span of a few seasons, Pam’s character develops from the humble receptionist to a more assertive employee who somehow finagles her way into becoming the office administrator. Pam’s responsibilities include but are not limited to: keeping Michael in check, assisting Jim in his pranks on Dwight, and showing little to no enthusiasm as a receptionist.
ISFJ stands for Introverted, Sensing, Feeling, and Judging. ISFJs are the “defenders.” Although they possess certain definitive traits, some of their qualities defy these traits. For example, ISFJs are sensitive people, and yet have excellent analytical abilities. They are normally more reserved, but have very strong relationships.
Let’s address some of the strengths that Pam and the ISFJ share. ISFJs are known to be reliable and patient. They not only complete their given tasks, but normally go above and beyond the requirements. Take Season 3, Episode 4: “Grief Counseling.” When a bird flies into the first floor window of the office, Michael tries in vain to revive the bird, and when he fails, plans a funeral in the parking lot. Pam sees that this means a lot to Michael and goes out of her way to craft a small coffin for the creature. She even prepares a speech in hopes of comforting Michael as he grieves. Pam is frequently going out of her way to make sure things are done to the highest calibre. 
In addition to being patient and reliant, ISFJs are said to be both imaginative and observant. Their quality of being observant often goes hand in hand with their ability to empathize with others. Pam notices each occasion when Angela buys Dwight his favorite candy bar, Baby Ruth. When she sees Angela is concerned about Dwight after his concussion, she intentionally updates Oscar on how Dwight is doing, so Angela knows as well.
Moving onto weaknesses. ISFJs are reluctant to change and are usually humble and shy. Pam definitely struggles with both of these, namely the latter. She rarely takes credit for the things she does around the office and she has trouble making her thoughts known. We do see, however, as the show progresses, she begins to grow out of her shyness. For example, during Beach Day, she is the only one who has the courage to walk across the burning coals, and once she does, she is no longer afraid to let everyone know how she is feeling. 
Pam’s biggest weakness in the beginning seasons of the show is her reluctance to change. How long was she engaged to Roy, you ask?? Three years. Then after they finally called off the engagement, they got back together during Phyllis’ wedding. Cuh-laaaassic ISFJ.
While Pam embodies all of the strengths and weaknesses of an ISFJ, the most clear reason she is an ISFJ is how she handles relationships.
“Defenders are most attractive when they are simply being themselves in a comfortable environment such as work, where their natural flow shows this kindness and dedication. Relationships built on established familiarity are a warm prospect for Defenders.”
So…Pam in a nutshell.
The Office Analytics 