Around junior year in high school, I became fascinated by a distant future where zealous aliens and super-soldiers made things go “kaboom” a lot. It was around this time as well that other young ladies became fascinated with a pair of immortal men who growled and sparkled a lot. As a result, I had a little mantra running along in my head: “Halo. It’s my anti-Twilight. What’s yours?”
In retrospect, it would have been as equally valid to say “Halo. It is my Twilight.” After all, while my peers were off falling for a vampire or werewolf, I was consistently strapping on armor to fight extraterrestrials. It may not have been the same fantasy, but it was the same method.
For this particular exploration, I will be looking at only the games of Halo. This is because they are the backbone and the core of the Halo lore and of the Master Chief’s story, and are the most prominent in the public eye. Any character development in the novels will not be addressed here.
Shell: Character De-evolved
In video games, a silent protagonist is common, allowing the player to be fully immersed in the game. All actions are controlled by the player; no one is putting words into his or her mouth. Thus the game character is rendered mute and without personality beyond the player’s. Most famous examples of these are Dr. Gordon Freeman and Chell, protagonists of Valve’s Half Life and Portal. For both of these, players seem to attach more quickly to the side characters, those who help or hinder your journey. People have more to say about Freeman’s friend and love interest Alyx Vance or Chell’s A.I. nemesis GLaDOS.
In fact Chell was almost replaced by a new mute protagonist in Portal 2. Test players at first responded well to this, until they met GLaDOS again. GLaDOS didn’t recognize the new human and by extension the player. This is where the players began to dislike it . I do not blame them. After all the effort I put into Portal, I would feel cheated if my old nemesis did not recognize me. Sorry; recognize Chell.
This reaction also extends to Bella and Master Chief. Through Halo: Combat Evolved and into Halo 3, Master Chief spoke in the cinematic cutscenes. Bella narrates the entirety of the first three books in the series. These are not silent protagonists, but they still were shells.
The Twilight of Character Development
“I left out a detailed description of Bella in the book so that the reader could more easily step into her shoes.” - Stephanie Meyer 
It is commonly accepted that Bella is a shell character. Her traits of uncoordinated, clumsy, and homely hit home with a lot of young ladies. In high school, our bodies begins to alter and change, often leaving us prone to gracelessness. Moreover, I have seen some of the most beautiful women in the world view themselves as unattractive. Not a whole lot stands out with Bella to distinguish her from another.
The characters that do stand out from the others in Twilight are clear. They are flocked to in teams. Team Edward and Team Jacob and never the two shall meet, unless you count Team Switzerland . The differences between the two are made as a contrast and their different personalities is the source of the teams. The merits of these traits have already been argued by many a source, and I won’t address them here. Have fun with Google.
Keep in mind, there can be characters with Bella’s traits that are fully fleshed out, and Bella could have been one of them. The gap between the two lies in how each of these traits affect Bella. Is there a particular reason she’s clumsy? Does it change her as a person or her relationships? Bella claims to be unattractive, but at the new school she is the girl everyone wants, especially Edward. How does she feel about that? Does it force her to reexamine her own worth or how she views beauty? Does she think they’re mocking her? She bites her lips and her nails out of nervousness. What caused her to develop the habit?
All this is left up to the reader. They get to decide for themselves how these things affect them.
Sorry; affect Bella.
As Empty as a Halo
“I think the advantage we have with the Chief is that he's kind of bifurcated; he is a strong, silent type with an actual machismo personality and a get-the-job-done tone of voice. He's also so quiet and so invisible, literally, that the player gets to pretend they're the Chief. The player gets to inhabit those shoes - men and women can apply their own personality. In a way, that makes it very easy for the writer; they don't have to define the Chief's personality. “ - Frank O’Connor 
“It's funny we don't then [at the end of Combat Evolved] show his face. But that's a device to keep the player invested in the character and keep the player from constantly being reminded that they're not a hero or that they have to be a boy or they have to be a girl, or whatever that is.” - Frank O’Connor 
Near the top on two “most overrated” lists for video game characters, Master Chief was intentionally a shell from day one [6,7]. At the end of Combat Evolved, the helmet is removed, camera panning up and away so that his face remains unseen. Even when in combat, he lets his companion A.I. Cortana do the talking. Once a cutscene is reached, he will speak minimally only to move the plot along or to give a one-liner like a boss.
In gameplay, it is hard to expect much. It would have to be a different sort of game for a fellow to wax on poetically about how the war makes him feel while gunning down aliens. While there are hints to how we should respond to the situation, it is always directed at the player. A cry from some extraterrestrial mandible sounds horridly inhuman. A wounded human ally will cry out in more familiar tones.
In Halo 3, Bungie upped the ante. There are moments when a distressed Cortana is crying out in pain during gameplay. She is not alone in this though; the parasitic Gravemind voices horrid threats and cajolings intermittently. What effect does this have? How does the Chief react?
Annoyed. Gravemind slows me down while trying to finish my mission, and he’s spouting of quasi-religious verses at me. Do you really think, big guy, that I am going to listen to what you have to say? You’re dead. You just don’t know it yet.
Concerned, too though. There’s Cortana, my dear friend who has stuck with me, snarked at me, kept me safe. Hang on Cortana. I’m coming. Because no matter what happens, no matter how rampant you become, I will always care.
Sorry; Chief will.
Sound familiar? It should. Master Chief and Bella have shared a similar stage in entertainment: one of self-insertion.
Did Bella ever grow out of her role as a shell character? I never touched the fourth book, never saw the movies, but from my friends who have, I’ve heard the answer is a rather resounding “no.” Master Chief on the other hand...
One of 343 Industries main ideas for Halo 4 that they were pushing like there was no tomorrow was “Chief is going to be put through the wringer.” When they said this, they weren’t just referring to the threat of death being bigger than ever. They wanted to take the Master Chief’s character to a new level. Put him into new situations that would test him and try him. They wanted us to get to know who the Master Chief is. Who John is.
On that end, 343 Industries certainly delivered. First cinematic cutscene we see a young boy, his face, his name: John. As it progresses we see not just Master Chief John-117 in action, but are also shown an image of him alone, hunched over, vision downcast to the floor. This is new, I think, and the voice-over continues:
“Do you think the Spartans' lack of basic humanity helped [their military prowess]?”
“Records show Spartans routinely exhibited mildly sociopathic tendencies, difficulty with socialization...”
“... the Master Chief succeeded because he was, at his core, broken...” (Emphasis mine)
As noted before, simply granting traits to a character does not development make. This prologue to Halo 4 was setting simply the stage.
Next thing noticed was the Master Chief’s awakening from cryo. Not the player’s awakening, the Chief’s. You view from his visor, but it is he who jerks awake who looks around, who asks Cortana, “Why did you wake me?”
When you do gain control of the Master Chief’s motions, he retains control of his words. Now when Cortana disrupts his Heads-Up Display in a fit of rampancy, John reacts. John promises to fix her. John reassures her. Because no matter what happens to her, John will always care.
The Master Chief has not begun to wax poetic on the war or why he is there. He is nearly as taciturn as before, even if some dialogue has reached into gameplay. In cutscenes he speaks only what he needs to and lets his actions say the rest. The difference is now what his words and his silence intentionally mean.
As Cortana considers her own mortality, the Master Chief is mechanically checking and reloading his weapon. Watching, the A.I. pleads him to “figure out which of us is the machine,” a contrast reiterated later, as countless civilians perish around them. Cortana weeps for their loss, asking that the Chief spare a moment for grief, “These people are dead.”
“And more will follow,” is his reply as he makes ready to move out.
Then the unthinkable happens. Cortana, who has been our companion and John’s companion for four games, dies. In her last moments, John begs her to stay. His voice cracks.
What 343 Industries has done in Halo 4 is answer the questions of “how does X affect Master Chief John-117?”
How do the deaths of the civilians affect John? He sees it as proof that they cannot fail on their mission, and not much more. They are dead now, so he must move on to keep others from meeting the same fate.
How does his “lack of humanity” that separates him from the other soldiers affect John? Emotionally, it doesn’t seem to. He accepts it as part of his duty and continues on, a notion that shown in his interaction with Captain Lasky and called out in the same scene.
How does Cortana’s rampancy and death affect him? He makes desperate promises to fix her. He constantly reassures her. And in the end, we seem him for the first time beg. Cortana’s death is devastating, leaving the victory nearly meaningless to him.
Even as the credits close on John quietly recalling Cortana’s words to him about his humanity, 343 Industries is not done establishing their dedication to his development from a shell character. Playing through on Legendary will reveal something never before committed to screen, the face of the Master Chief. John’s face. This, combined with him speaking throughout the game, shatters the illusion that Bungie had aimed for for so long. John has moved beyond a character that I can simply insert myself into. As a result, like Frank O’Connor said, I am constantly being reminded that I am playing a man, a very specific and defined man who is not me. But the other result is this - I am far more invested in John as a character now than I ever was before.