Some people call the first two functions your "Super Powers" (e.g. "DaveSuperPowers" who did some popular MBTI videos on YouTube). I like the concept as I think there's too much emphasis placed on being well rounded in this world. Noticeably it's the ES types in particular who push this idea, and it corresponds to their preference for "taking it all in".
Anyhow I love the concept but, at least for the INTP (as far as I've thought about), the SuperPowers really are the top three, not just the top two, namely Ti-Ne-Si. That leaves Fe as the trickster and outsider, still part of the system as it provides the overall motivation for the trio but not part of their day-to-day activities.
This point is worth a separate thread - posted.