I will write down multiple explanations for certain topics. They will sometimes conflict with each other because I am trying to look at Nate in more than one way.
***Disclaimer: I do not claim that my interpretations are set in stone or the only right way to see his character. This is just my personal take on him. You are allowed to disagree with me.***
Spoilers under the cut.
PSYCHOPATHY AND MENTAL ISSUES
Everyone can agree that Nate is crazy. However, most people use the turn “Psychopath” to describe him. I wasn’t sure how accurate that term was for Nate because even though I agree that he has something wrong with him, “psychopath” didn’t really feel right to me for some reason. But then again I don’t really know much in this field so I decided to research actual psychopathic personality traits.
There are many different ways to assessing psychopaths, but I’m only going to use the “gold standard” test known as PCL-R (Psychopathy Checklist-Revised). Each item on the list is rated from 0 to 2, with 0 being not related to at all and 2 being a good match. This is what I put for Nate:
Glibness/superficial charm _ 0: Though he does admit to trying to loosen Russell up, it was clear that most of the time Nate wasn’t just saying things to flatter him or pretend that he cares. He was either genuinely interested in what Russell had to say or would change the topic to something that he wanted to talk about. He would also call him out on being stupid or stubborn.
Grandiose sense of self-worth _0: None of what he says or does suggests that he thinks himself as being higher than other people or that his life is worth more. This is shown when he risks his life to save Russell even if the latter tries to kill him. He wouldn’t have done that if he thought he was worth more than the other.
Pathological lying_0: The only time he ever lies to Russell is when he says that he’ll cover him, and even after that he keeps his word about protecting Russell. That one time isn’t enough to call him a pathological liar.
Cunning/manipulative_1: The only time Nate manipulates Russell into doing anything was when he attempted to get Russell to tell him if a zombie used to be hot by almost getting him bitten. This moment alone deserves a number because of the extreme danger of the situation and the implied length that he will go to if he really wants something.
You might also think that the time when Nate pulls the gun on Russell at the diner would be another case of manipulation through the threat of death. However this can not be said with certainty because it appears as though Nate is more caught up in his thoughts of killing the couple than threatening Russell. The threat might not have even been intentional, just a result of a Nate delving into his insanity. Also, whether or not he agrees with him, it is clear that he never intends on hurting Russell.
Nate isn’t cunning, but he is smart when he needs to be.
Lack of remorse or guilt_2: If he feels like you deserve it, he will kill you without a second thought or any lingering feelings after you are dead. The murders of the elderly couple are the prime example of this.
Emotionally shallow_0(?): Having shallow emotions means that a person does not feel deeply about things, not being able to feel emotions that would allow one to connect to other human beings, even if they can feel more self-serving emotions (definition here because I didn’t originally know what this meant).
Nate does come across as not having shallow emotions, but it is hard to say whether or not this is really the case.
Callous/lack of empathy_1.5: Again, this one is a bit tricky. He clearly doesn’t empathize with the elderly couple that he kills, refusing to completely understand why the old man was trying to kill him. On the other hand, when Russell was very emotionally bothered in one way or another, Nate could understand why he was like that and would attempt to be supportive in his own way some of the time. It is possible that he has selective empathy (which I will discuss later).
As far as being insensitive and cruel, Nate tends to flip flop between being very callous (e.g not sparing the innocent elderly couple) and caring (e.g wanting to take care of Russell), which is quite odd.
Failure to accept responsibility for own actions_0: When Russell reacts negatively to his action, Nate will completely accept the fact that it was something that he did. From the silent treatment in the truck to having a gun pulled on him, he never says it wasn’t his fault for such a reaction.
Need for stimulation/proneness to boredom_2(?): This might seem obvious because of how Nate first mentioned that he was bored, his constantly taking about women and his “needs”, but in actuality it’s hard to give a definite answer. If he hadn’t had any companions after his friend got killed, he would have been alone for quite some time (143 days!) and that isolation would have led to restlessness and boredom. This could be apart of Nate’s personality or it could have increased as a result of having no one else around.
Parasitic lifestyle: N/A, not enough information
Lack of realistic, long-term goals: N/A
Impulsiveness_1: He impulsively decided to pick up Russell and use the zombie to scare an answer out of him. Both actions should have taken more thought before acted upon but weren’t.
Irresponsibility_2: Very much so. He picked up a hitchhiker that could have been dangerous, he drinks and drives, he lets a zombie attack Russell even though it could have bitten him, he doesn’t make sure that he has enough bullets in his gun, and he doesn’t right away cover Russell from gunman’s fire.
Poor behavioural controls_2: This man doesn’t seem to have a filter for the things he shouldn’t say or do. If he wants to do something, no matter how horrible or dangerous it is, he’ll do it. He understands that he has a problem with this, evident by the times he apologizes to Russell for his behaviour, but only seems to be willing to fix it up to a certain point (He wants to make a new first impression on Russell when he has the gun pointed at him, but he doesn’t change his mind about killing the elderly couple if Russell disagrees).
Early behavioral problems: N/A
Juvenile delinquency: N/A
Revocation of conditional release: N/A
Criminal versatility_2: It’s somewhat scary how adaptable Nate is when it comes to being in danger and committing a crime. In both dealing with Wyatt and Eddie on the road and the gunman at the diner, Nate was able to react quickly and with a vengeance.
Many short-term marital relationships: N/A
Promiscuous sexual behaviour_2(?): The way he acts highly implies this, though we never actually know if this is really the case.
Now, out of the possible 40 points that can be had, 30 is needed to be considered a psychopath in America.
Nate only got 15.5.
He is way under the American break point for being a psychopath.
Now you may be thinking, “What the hell!? But this man is crazy!!! Besides, a few of them say N/A!”. You’re right, there is something wrong with him, but it’s just not this. And the ones that say N/A are the ones that weren’t shown in the games a therefore could not be used to judge him.
"So what exactly is his problem?"
I’m not really sure. However, I do believe that he wasn’t always like this. Maybe he was always a jerk, maybe he used to be a good person, but in one point in his life he used to be relatively normal and then something happened that caused him to progress to this point. It would explain why he has so many issues without being completely mentally ill.
There are many different reasons as to why he could have gotten to this point, a few being:
Whatever the reason, Nate is now a really dangerous human being.