Socionics
Cousins with MBTI, however, they do not want to associate with one another. Probably a pseudoscience.

Socionics claims there to be 8 information elements (IMEs) and 16 types. These 16 types of information metabolism(TIMs) interact with one another in 16 ways.

Each TIM possesses all 8 IMEs, in different slots in their cognition. They value certain IMEs above others, and they are stronger in certain IMEs than others.

These 16 types are also divided into 4 quadra of 4, each sharing the same valued IMEs. Those who share a quadra are where long term relations are most likely to flourish. They are the Alpha, Beta, Gamma and Delta Quadra.

Warning: Socionics is rather complex. Please do not try at home. Unless you want to. Then maybe you can.
IEE: Hey guys guys guys I found this socionics thingy
ILE: I know that! You going to run off in search of your SLI boyfriend now?
IEE: Hey! Not funny!