ENFPs, especially if they’re also 4s, can crack your emotional codes better than any other type. Almost right off the bat, you feel like you can tell them anything, all your secrets you’ve never told anyone else. It’s not something ENFPs even have to think about, it comes naturally, effortlessly; look what Vesper (a clear cut ENFP) did to James Bond (a hardcase ISTP) in Casino Royale; he was totally in her power by the end of that movie.
INTJs are especially vulnerable because ENFPs connect with and activate the INTJ’s tertiary Fi, which is like their Achilles heel; before he knows it, the INTJ "mastermind" is in her thrall. INTJs are vulnerable in the emotional realm; even for more emotionally aware 5w4 INTJs, it’s still alien terrain. A mysterious and fascinating moonlit world to explore from the armchair, to be sure. But it unravels them, causing them to lose their bearings, when they’re forced to experience it firsthand with someone who reigns supreme there.
Put simply, INTJs are out of their depth with ENFPs.