INTJ type 4's are very rare. They are emotional, but the emotions run under the surface... it's not obvious. You might notice that they wear a unique style of clothing that is them, but very functional. When it comes to their work, they will go out of their way to make sure it is original to their style, and keep themselves from being in a specific niche. They are very creative in solving problems, and want to make sure it is done their way, with their own flair. They will tend to romanticize intellectual pursuits and ideas, and if they have artistic abilities, will produce work that is reflective of romanticism, yearning, but the romanticism goes through a brain filter. You will notice that an INTJ 4 will have an air of refinement and elegance to them, very sophisticated, yet they are soft-spoken. While they are confident on what they know, don't know, and their abilities, they might be hard on themselves, especially when they don't achieve the desired outcome of their goals. INTJ 4's will never, or rarely, compromise who they are and what they create just to make it more popular. They want to adhere to their inner values. INTJ 4's are very unassuming and may have a difficult time promoting their vision. They feel much more comfortable being in the background. You might notice an INTJ 4 will have a wannabe rebellious streak, and their form of rebellion will be an intellectual/artistic adventure. They might read literature that contains individualistic themes, presents a cynical view of authority, and will tend to like art that varies from the traditional to things that have an almost dark quality to it. They might like listening to music that is a bit intense, but also like music that is slow and heavy, and the delicate and beautiful. They are difficult to please when it comes to artistic and musical tastes, and may not like what is trendy, they avoid trends at all costs. INTJ 4's are also in their own worlds... they may find books, music, and art better than the chaotic/noisy world around them.
Never argue with an INTJ 4 though... be prepared for them to get a bit defensive, and temperamental.