Misunderstood man or malicious murderer? Abused child or abusive husband? Loving spouse or lonely adulterer? Throughout Gone Girl, Nick Dunne appears to be many things. Some of them we know to be true, some of them we don't—the surprises, shocking revelations, and personality twists are all part of the fun of seeing his character unfold.
An unreliable narrator is a first-person character who, for one reason or another, can't be completely trusted. In The Catcher in the Rye, for instance, Holden Caulfield is so angry at society that we can't be sure of whether he's really telling the truth or just being an melodramatic teenager. And in Anthony Burgess's A Clockwork Orange, Alex's obsession with violence leads us to believe something's not quite right up there in his head. But those are just two examples—Nick Dunne is yet another.
Whether they're holding grudges, chronic liars, or just plain insane in the membrane, unreliable narrators make for both fun and frustrating characters, and Nick is right up there with the best of them. He lies to the cops—on at least eleven occasions (7.84)—and he also withholds significant information from us as readers. He crafts a false story about where he was the morning that Amy disappeared, saying that he was at the beach while disclosing to us that he actually never goes there (7.67).
Perhaps the biggest offense occurs when, just when we are starting to believe his story, he reveals that he's having an affair with Andie, one of his students at the community college where he teaches (19.2). While he insists that he didn't kill Amy, evidence keeps popping up that suggests otherwise—at least until we find out Amy's alive, at which point we're pretty much forced to believe him. Still, he's not trustworthy, and even if he didn't kill her, there's probably still plenty he hasn't told us.
Gone Girl is one of those books where you need only look to the main characters' family background to see the root of their dysfunction. The Dunne family is no exception. While Nick does make the decision to move back to North Carthage when Go tells him their mother is dying, he does so with a love/hate relationship with the place he came from. There are happy times in the place he grew up, but the sadness and uncertainty seem to outweigh it all.
On the plus side, Nick's super tight with Go. She's his best friend and confidant, and moving home gives him the chance to relieve her of the weight of going through their mother's death alone (1.13), not to mention making their dream of opening a bar a reality.
According to Go, Nick was also the favored child of the family, who "got the best of everything" because he was the firstborn their parents expected, not the surprise twin (3.8). Nick was definitely a mama's boy as well—as Amy states in her diary after his mother's death, "His mother had always mothered him" (24.24). (To be fair, Amy's diary should be taken with a grain—make that a handful—of salt. Be sure to read her analysis in this section for more on why.)
On the other hand, Nick's relationship with his father seriously damaged him. His dad's unpredictable behavior and anger issues, as well as the pressure of his expectations, have turned Nick into a chronic people-pleaser, a flaw that causes many of the faux pas he makes during the investigation.
For instance, during the initial press conference about Amy, haunted by his father's axiom that "Men don't cry" (9.53), Nick is so obsessed with trying not to show emotion that "the words came out clipped, like I was reading a stock report" (9.52). So instead of crying—a totally appropriate response to your wife going missing—Nick instead comes across as uncaring. While he is definitely not a kid anymore, his childhood—particularly his father's role in it—is still totally capable of majorly messing things up for him.
While Amy makes a lot of threats about what she'll do if he leaves her, Nick ultimately stays because of his fear of becoming his dad—especially after she announces her pregnancy. He sees the baby as his chance to undo the damage his father did. "I didn't just want a child," he tells us earlier in the story. "I needed a child. I had to know that I could love a person unconditionally […] That I could be a different kind of father than my dad was. That I could raise a boy who wasn't like me" (39.58). Yup—this dude is definitely driven by his daddy issues.
Maybe this is kind of a duh point for us to make, but Nick's relationship with Amy is the most critical factor in his journey as a character. Nick tells us that he initially fell in love with Amy because "she was fun. She was funny. She made me laugh. And she laughed" (7.84)—somewhere along the line, though, things changed. The laughter stopped. She got distant and moody, became "a pile of skin and soul on the floor" (7.84). Yikes.
Since the book interfaces Nick's thoughts with Amy's, we know that this change was due to Amy's exhaustion in keeping up an act, pretending to be the "cool girl" she wasn't in her heart of hearts. And of course the move to Missouri probably didn't help much.
One really cool thing about Gone Girl is that we get to witness Nick's emotional waves toward Amy as he investigates the mystery of her disappearance. In particular, doing their anniversary treasure hunt—at least before he knows her sinister true motivations—draws him back to her in a way he didn't expect. "I'd fallen in love with Amy because I was the ultimate Nick with her," he explains. "Loving her made me superhuman, it made me feel alive" (29.111). And then, just like that, he learns that she's actually framing him and hates her again.
The problem is that Nick's initial love for Amy doesn't come from a healthy place. Quite the opposite, really. Amy's perfectionistic attitude, Nick says, "made me believe that I was exceptional, that I was up to her level of play" (29.112). It's probably safe to assume that she fed the same ego his mother instilled in him as a kid. It's this mutual explosive egoism that causes them to begin one-upping each other once Amy returns.
At the book's conclusion, Nick describes himself as "rising to my wife's level of madness" (63.40). While the life Amy offers him seems awful, Nick is probably not just staying because of their child—he sticks around for a while before learning she's pregnant, after all. Instead, he's staying with Amy because he literally can't exist without the tension she brings to his life. In Go's words, the two of them are "addicted to each other" in a highly destructive way (63.30)—and looked at from this angle, Nick isn't a victim of Amy's so much as he just can't quit her.