socionics and mbti is not fundamentally different
in this post i will prove through socionics's "intertype relations" how you can't just go call some infps in mbti iei and others eii by vibe typing or whatever.
in socionics iei (NiFe) is "most compatible" with sle (SeTi) and this is called a duality. the reason being iei has VALUED but weak Se. naturally then, sle is the perfect help with that strong Se to iei.
the same way, sle has VALUED but weak Ni. naturally then, iei is perfect help for him with that strong Ni base. (notice how the redhead on the left has some dollar bills and other papers and stuff on her hands which symbolize her future oriented and planning ni nature but she also drops some of them cause se inferior)
THEN, they help each other through their next function in line too. sle helps iei with his "creative" ti because sle's ti is always on and mature and responsible. it understands iei's more sporadic "activating" ti and supports it in a non bossy way, like a "good parent" or teacher.
in the exact same way, iei provides fe creative to sle. for example when sle triggers others with his trolly fe, iei steps in and softens the stuff in the most elegant and non bossy way so sle do not get annoyed with that puerile "fe child" of his.
NOW! what about SLE and EII though? well, that's the "WORST" intertype relations in socionics and called conflict.
in socionics, EII (the lil' princess on the right) has "Se vulnerable" aka polr aka blindspot. so of course an Se dom will be too impactful, too forceful, too direct for EII.
so "as an infp in mbti" ask yourself: how can you be an IEI in socionics and SLE can be your dual? you like neither SE nor Ti. even entps and their ti hurts you in the feels from time to time. imagine sle's much more direct ti through se. thus, you must be an EII.
thus, any TRUE INFP in mbti with te inferior and si tertiary, will be always an EII.
don't forget: inferior in jung was anima / animus and socionic's "dual-seeking" concept comes directly from there.