So my older brother happens to be an INFJ. For the most part we've had a fantastic relationship throughout childhood and into out adult lives, but I've noticed some peculiar behavior - some of which I'm already aware can be typical of INFJs - and I'm curious to see how many other INFJs (or NFs, in general) share these behaviors, and what your motivation behind them might be.
The first his tendency to wear social masks, faking traits that aren't really prominent when he's just being himself. Most often, this takes the form of replacing his I with an E, and his F with a T.
The second is his tendency to resort to petty or juvenile behavior when in an argument, or, occasionally, to assert a form of social dominance (via antagonistic behavior) over others. Often even when proven wrong, he'll attempt to change the subject, and rarely admit actually being in the wrong. Other times, if he's done something that's plainly rude or inconsiderate, he'll refuse to apologize, even if he can't deny that his actions were in the wrong. Similarly to his behavior when losing an argument or debate, he begins to avoid the topic, and will sometimes go so far as to physically leave the room before ever admitting any form of defeat, or regret for past actions.
I've never really grasped his motivation behind these behaviors, so any insight would be appreciated.