Père Leon: What's your name?
Chouchou (a man): Chouchou
Frère Jean: [giggles and sneers]
Chouchou: [upset, self-conscious, embarrassed]
Père Leon: Oh don't mind him, he just needs things to be... arbitrarily correct.
Doesn't translate quite so well into English, but I hope you see the point. The Frère Jean character is very much ISTJ, and needs things in the environment around him to be stable and 'arbitrarily correct' - that is, correct as he defines the term, according to his prior experience, no matter how limited or dubious.
And he needs to be seen as Always Being Right. Dave and Adam really can't stand it if they're proven to be wrong about something, or if something they say confidently believing it to be the One Correct Answer, is conclusively shown to be wrong - they both just fall to pieces, totally embarrassed and ashamed and they usually leave the room as soon as face allows it and go beat themselves up in another room. And they're both TERRIBLE losers at things like Scrabble, and absolutely absurdly competitive with them. Like Dave will actually spend ages taking his turn when he's playing against my 8 year old daughter, because he NEEDS not just to beat her but to THRASH her. He can't even 'let her win', even though he can't seriously believe that anyone questions the fact that he's capable of beating her.
So that's how I think that Si-Te can be just as strongly affected by their environment as Si-Fe.