The relationship of Se-Ni (if we’re excluding judgment) are two perceiving functions that aimlessly give each other perceptual insight beyond reason

Sensation apprehends reality by subconsciously perceiving absolute elementary facts, BUT these perceptions of the absolute are transmitted to perceptual consciousness. Since sensation in this context is extraverted, it should merely perceive absolute elementary facts immediate to the situation outside oneself, as extraverted functions are more deprived of an entirely subjective influence

On the other hand, intuition should involve perception by way of the unconscious (receptive to unconscious contents)

Intuition in the introverted attitude orients toward placing contents of the unconscious at centre of perspective, as it is directed to the contents of the unconscious. It is drawn not toward the object itself but with what effect the presence of such has released within themselves - they are receptive to their unconscious perceptions that arise from the absolute, but in nature it is not drawn to repurposing it

Knowing this, the relationship would likely be:

Se gives Ni absolute elementary facts for which Ni can use as a basis for its perceptions/for which they intuit

Since Ni is the third function + in this situation it is strictly the perceiving axis, Ni should lack perspective therefore suffering mostly on the Se spectrum. Se would suffer the same problem—only given perceptual insight from Ni which is not of value

It is a complementary, yet broken relationship - complementary in the sense of oppositional attitudes, but each lacking an insight to gain from each other

Hope this helps somehow - I am only mentioning perceiving axis