Here is how Filatova approached Duality descriptions in her english socionics book. She describes how each type's Weakest function (Suggestive) works like a lock, and each type's Strongest function (Base) works like a key.
IEI - The Romantic
: Romantic daydreamer who easily forgets reality for the sake of dreams which are the source of inspiration and understanding life.
: Follower, not leader; difficulty manifesting initiative and willing himself to do something or to undertake responsibility for something.

SLE - The Organizer
: Volitional action; Irrepressible lust for activity; sportive tonus and decisiveness; capability of not missing initiative and winning in competition.
: His/her courage very often over weighs caution. Sometimes he lacks inspiration. "For what sake am I doing this all?". He cannot self-inspire because of his mistrust for everything vague, mysterious and unearthly, and is thankful to those who can inspire him.

LSI - The Structurist
: Finds a stable structure and obeys its laws; systematic and concrete thinking.
: Poorly understands others' emotional reactions; secretive; often meets difficulties in communication.

EIE - The Performer
: Brilliantly manipulates other people's emotions, just like a conductor conducts an orchestra; affects people using a broad range of feelings.
: High emotionality warps judgments; logic subjugated to emotionality.