Hello! Thank you for the ask. I’ve met several INTPs. So, instead of healthy vs. unhealthy you guys get immature vs. mature.
Immature INTP
1. My first impressions of them: cool, collected, confident, well-liked, knowledgeable, child-like when happy and in their element.
2. My current impression of them: a fucking shit storm. That really sums it up, but I’ll elaborate for the fun of it. Never considers the impact of their actions, completely ignorant to their own feelings, no idea how to appropriately respond to their feelings and is fully willing to hurt everyone else in their endeavor to not take responsibility for any of their emotions or actions, irresponsible, can’t communicate to save their damn life even if you’re asking a rather straightforward question, completely inept at starting or holding a conversation unless you manage to pry enough on a topic they find interesting, incompetent at handling any practical or necessary matters in life, doesn’t care about anyone unless for some mysterious reason they decide they actually like you at which point if you accept friendship you get dragged into the shit storm, shockingly still well-liked by quite a few, extremely low self-confidence but no attempt to improve anything, entertained by being a low-key dick, completely unmotivated to do or solve anything, and prone to not tell you literally anything even if it has a significant impact on you (ex. this fucker would break up with someone and not bother/forget to tell them), oh and extremely knowledgeable and in-depth opinions on a few specific topics.
3. My relationship with them: ex-friends by my intentional decision and action.
Mature INTP
1. My first impression of them: quiet, cunning, well-spoken, relaxed, personable, quirky.
2. My current impression: (same as above, plus) incredible, cuddly, friendly but critical of others, intelligent and competent, very skilled, considerate and actually very warm and supportive about emotional matters, well thought-out opinions based in reason and sometimes science but still listen to opposing arguments and when appropriate with understanding or while keeping their opinions hidden, one was from a different culture and actually rather strictly upheld social norms while the other threw ALL social convention to the wind except for that which was outwardly (reasonably so) hurtful to others, rather reserved around those they don’t know or don’t like, very sarcastic, funny and uplifting goofy moments, very lovable and charming all the more so the more you get to know them, extremely dedicated and focused when working.
3. My relationship with them: good friends that I desperately wish I wasn’t drifting away from due to physical distance.