I'd say for me it's my balance on S and N. I mean, technicallly, INFPs have both their perceiving functions in the middle, but still, they are balanced. On one hand, I am big picture and possibility oriented and love playing with ideas as well as noticing patterns all the time, but I am also very exploratory in the sensory realm and am observant and not particularly out of touch of reality(and I realized introspectiveness doesn't equate to the overt daydreaminess associated with Ns). It's interesting, I feel like I have a S-ish attitude to my Ne and an N-ish attitude towards my Si. My Ne wants to embrace all the possibilities in my environment, what's hidden and also not wanting the same routine and also being stirred into curiosity with by the sensory(like noticing a detail in my environment that I need to know more about). My Si, I think about a lot how my past and my present has affected me as a person and what parts are gone and what parts are still lingering. Taking the time to introspect about things that have happen in my life, imagining new scenarios out of situations that have happened before. That confirms my Fi-Si typing in OPS I think, because my Fi and Si have a stronger interaction rather than my Fi and Ne, my Ne is kinda just like, "What's up, you guys?". I guess I fall out of the box with that too, since jumper types are a little more rare(jumping being have a heavier reliance on the tertiary function while your aux function still being your hero). Enneagram wise I don't really fall out of the box, except that it feels like I have no head type sometimes. Swear I have equal IVs at times, though.....