Socionics - Socionics intertype relations describe relationship between Psychological Types of people and not between the actual people. This is the reason these relations are called "intertype" relations. The relations between actual people are complicated and depend on many different factors. The intertype relations, however, form the core of any relationship and describe various degrees of psychological compatibility between people according to their Types.
Words from the CLab - Cultivating characters through psychological buildings is part of the science behind literary and fiction writing. By utilizing everything learned about evaluating and understanding personality types, this behavioral tool is the first step in creating a dynamic and memorable character. As practice makes perfect, building various characters using these methods makes authors more versatile and creative in their brainstorming. Understanding such methods builds on the author's personal character and is an asset to be used in their literary repertoire.
To see more about Dr. David Keirsey's views on the four temperaments read more at The Four Temperaments.
To see more about the various compatibility levels between different personality types read more at Relations between Psychological ("personality") Types.