The intertype relationships, ITR, is a very important part of socionics, that to a large degree lacks in MBTI. The closest alternative is Keirsey’s idea of the perfect match, where all letters but S/N should be different, or the other alternative that can be found, where it follows the same pattern as with Keirsey, but the T and F could either change or be the same.
In socionics however, there is more than just a “perfect match”, a system that describes the relationship between each type. There are a couple of important things to note with those though, before diving deep into what they mean.
They are only taking functions into consideration.
The system of ITR are only working with what information can be put into a system, namely how the functions interact with each other. This is how the whole system is built, but it also limits it, since personal differences plays a huge role in who we work well with.
The descriptions are static.
A problem every description, and ITR is no exception, is that it’s static. It doesn’t consider personal differences or nuances, how a person is raised or other experiences they have.
Both of those aspects are very important to consider when reading about the intertype relationships, or they will be misunderstood.
Why it’s useful.
On the other hand, there’s a big strength to the system of intertype relationship. Together with the concept of quadras, this puts the type into a bigger picture, rather than just being a type in isolation. It also helps to understand the interaction between types, and how the dynamic works. What you give to the other person in the form of cognitive functions, and what the other person gives to you. It’s descriptive of the weaknesses and problems each pairing has, which makes them easier to avoid.