Yeah, Walter is basically an ass [well, maybe I should be more explicit -- he's egotistical, controlling, judgmental, tyrannical on the level of a child's Freudian ID] who was hamstrung and/or self-smothered at a young age and shoved down his wildly raging ego without ever actually confronting himself and experiencing any kind of change -- it was simply caged, not tamed and altered in any way. So once he gets cancer, he decides he has nothing to lose and dismantles the cage... oh hey, look at what has been there all his life but now is REALLY seething...
I still think Jimmy is a good guy at heart, merely flawed. A lot of what threw off his constraint is as you said just how his brother kept kicking him in the teeth -- a brother who Jimmy dearly loved, desperately wanted love in return from, and never consistently got it... and it tied into his beliefs about family solidarity, fair play, giving people chances, etc. It all got seared in the endgame with Chuck, and that particular ending kind of left him without any kind of anchor. Despite how much he loves "making the sale" however and his life of pulling one over, in the end I think he's been through so much misery that he wants something more enduring. He lost a lot by the end of Breaking Bad and as Gene he seems to reflect that he's not happy with where his decisions led him.
Mike reminds me of a ronin (just more low-key). He knows he broke faith, and it cost him his son (as well as a friend), and he still hasn't gotten over it (it boils up with his grand-daughter, leading him momentarily into self-destructive tendencies as ways to punish himself for his crimes)... and now he just seems resigned even to Nacho who he essentially says, "You bought into this, now you gotta pay for it / live with it." But there's still empathy on some level there, he'll help him once they get the job down with Lalo.... for the sake of Nacho's dad. Mike knows what it feels like to have people he loves hurting because of Mike's choices in life.
So I've seen some commentators wondering why Mike is sticking with Gus. It seems generally pretty simple to me? He's lost faith in himself, is self-punishing, and sees no real escape from his past actions. IOW, he feels he is one of the walking damned, can never escape, and so he just embraces what amounts to his punishment -- living with knowledge of his mistakes and doing penance that can never be complete, trying to keep his granddaughter from harm, and maybe one day being allowed to die and find peace.
Anyway, he definitely strikes a more tragic figure... competent, generally amicable, professional with his work, paying for his past choices and unable to escape, so he buys into it with a level of dour fatalism.
Keeping in mind I have only watched up through season 4...
I agree, Jimmy seems at heart a good guy. He tries over and over again, throughout the seasons, to do the 'right thing', to overcome some of his leanings, play it straight, etc, but ultimately just hangs his hat and goes the 'screw all of you' route and just settles into a life of questionable morality.
I love the dynamic between he and Rhea (gah - blanking on her character name all of a sudden).
Gah - must segue into mbti, because THIS show is a great example of why I think mbti can be interesting, and why I dislike how it plays out in theory and in intellectual discourse such as on this forum. This show has perfect examples of many contrasting temperaments and how they interplay, and yet none of these characters - of widely varying temperament - seem 'deficient' to me. None seem intellectually stunted, 'ooh I wouldn't want to be THAT type' (well, maybe with Jimmy...lol haha j/k ... kind of haha), they are all enviable to some degree, all highly competent and brilliant in their own niche and way of seeing and interacting with the world. You see the brilliance and enviability of many sensors; you see the far-sightedness but also tendency towards grandioseness and callousness and tendency to neuroses or sheer stupidity/naivety of several N's in the face of real-world things that happen at the blink of an eye and need to be acted upon literally instantaneously.
Nacho is a wonderful ISTP imo; very good deep down but aware of his position and as you have said, just at this point trying to make the best of things and ease the situation from any innocents or anyone he could keep away from it. Smart. Thinking.
Mike also, I assume ISTP (else what would it be, ISTJ? I suppose, but skillset/ natural ability wise SP seems more fitting). I too feel Mike sticking things out with Gus makes sense. To me Mike is probably the most honorable man in the entire show --- he follows through with everything he gets himself into --- even if he realizes he's 'screwed', similar to Nacho. I think his personal code is such that he feels he needs to accept the responsibility of his choices -- and live through the consequences. Perhaps a type of self punishment, ie, thinking he deserves it, perhaps.
Rhea, TJ, to Jimmy's obvious ENTP. Contrast Jimmy with Chuck (clear NJ) imo , and Hamlin (epitomizes FJ imo, probably NFJ), and Jimmy's self is going to be prone to puppeteering by Chuck - which he does. Gus, INFJ I think.
Even the seedy uncle or whomever who shows up to try to attend to the cartel's business - fast-moving ESTP, smart, really quick on his toes, reads the situation well and pounces. The 2 hitmen-twins = creepy. haha.
I even enjoyed the whole side story in season 4 with all of the germans; I felt for the german leader and the bind he ended up being in.
Anyway I don't expect everyone to agree with all of these typings of mine, but the point is, it's a great show to watch the psychological interplay between people of very different temperaments and abilities/perceptions, all with clear strengths/areas of brilliance, all with shortcomings.
Anyway, love the show. And love the depth of characters.