Chrom
You knew it was gonna be Chrom. I wrote a long essay on why I like Chrom a while ago, so if you missed it, this is essentially that essay.
First of all, I feel that how a character reacts to and changes because of a situation are great indicators of a good character, more so than just a list of personality traits. This is important to Chrom, as it is where I think his character truly shines.
As a bit of context, I'll first describe Chrom's early life, as it lays the foundation of his character early on. During his childhood, Chrom's father waged war against Ylisse's neighboring country, Plegia. His mother is implied to have died when he was very young, around the time Lissa was born. The war against Plegia only ended with the death of Chrom's warmongering father, and his older sister Emmeryn was made Ylisse's new Exalt. At first the citizens hated her, hurling both harsh words and harsher stones. Emmeryn never faltered, however, and eventually earned back the love of the people, mending the scars of the war their father started. Chrom comments that he would have never repaid their abuse with kindness, but recognizes that Emmeryn is a better person for it. As such, he decided that he'd be as great a leader as he could be.
This eventually led to Chrom forming the Shepherds, a group of soldiers acting as a sort of elite squadron of Ylisse's army, with Chrom serving as their commander. And this is where one aspect of Chrom's personality comes into place: Chrom is a "father to his men". He legitimately cares for each of the Shepherds and notices the areas in which they excel. Despite being royalty, he never lets that get in the way, as all are equal on the battlefield. For example, Vaike says exactly this in his support with Lissa.
Vaike:
I've dealt with a lot of fool ignorance since I joined the Shepherds. People are always askin' who I think I am, a commoner lording it up with princes. I've had it from lowborn and highborn alike. ...But never Chrom. It's like he doesn't care where I'm from, so long as I handle myself in a fight.
Another example of this can be seen in the Summer Scramble DLC, where Chrom has a conversation with Stahl. Chrom takes note of Stahl's performance in battle, mentioning how proud he is of how far he's come. Stahl, overjoyed, ends up working himself to near exhaustion in an attempt to live up to Chrom's praise. Chrom then stresses that he doesn't need to over-exert himself, as it would only lead to Stahl getting killed by the enemy. This reaffirms one of Chrom's biggest drives: to become a better man than his father was. Whereas his father conscripted untrained villagers to fight and die for him once his supply of soldiers was burned through, Chrom recognizes the value of the lives of all of Ylisse's people, including his soldiers. Chrom's father had his people fight for him, while Chrom himself fights alongside his people, knowing their limits and never pushing them too far.
One of Chrom's most informative support conversations, however, is his set of supports with (male) Robin. One facet of Chrom's character that often receives criticism, both in universe and in online discussions, is his incredibly trusting nature. Robin comments on this, stating that Chrom taking him in in his amnesiac state was a foolhardy move, as it could have been a massive security risk. Chrom simply replies that he can't change who he is, and that he saw a person in need and needed to help them. Later, Chrom is confronted by a mugger who flees upon seeing Chrom draw Falchion. Chastised by Robin once more, Chrom promises to take more precautions in the future...only for Robin to see that Chrom is taking two or so soldiers with him on patrol. Not satisfied with Chrom's menial attempt at safety, Robin confronts Chrom once more, leading to this exchange:
Chrom:
Look. I understand enemies could be lying in wait to try and kill me... But there could also be others who need my help! There's a war going on, and people are suffering. I can't ignore them. I won't.
Robin:
So why not send your men to search for these hapless innocents?!
Chrom:
Because.
Robin:
Becauuuse...?
Chrom:
Because...of you. If I hadn't been there—if Frederick alone had found you—would we have ever met?
Robin:
...Probably not.
Chrom:
You see? And it's not just you, Robin. It's everyone like you. I know going out there exposes me to danger, and I haven't always been careful. But it's a risk I'm willing to take in order to connect with the people. To forge bonds.
Robin:
Bonds? Between who?
Chrom:
You and me. Me and the others. The villagers we've met, the world we've seen... Such bonds are the true strength of this army. Without them, we're lost. Others may disagree, but that's one benefit of leadership: I make the final call.
Chrom views the strength of his army, and his country, as a measurement of the bonds he's created with the Shepherds. While this may at first seem like a cliché power of friendship moment, it fully illustrates the dramatic difference between Chrom and his father. His father used his people and his troops as lifeless pawns, simply means to ends, and himself as their ruler. Chrom views his people as his equals, and himself as their leader. One other thing to note is that Chrom instinctively trusted Robin despite the amnesiac being clad in Plegian robes, with Plegia being the country Ylisse has been at odds with for over a decade. Once again highlighting the difference between himself and his father, Chrom thought nothing of this. After all, a person is a person, borders be damned.
However, Chrom's devotion to his friends and family do end up coming at a great cost. During chapter five, King Gangrel of Plegia stages a kidnapping of Lady Maribelle, the daughter of the duke of Themis in an attempt to accuse Maribelle of illegally crossing over into Plegia. Emmeryn, Chrom, and the Shepherds offer parley in an attempt to reason with Gangrel, but Gangrel wishes to put Maribelle to death...unless Emmeryn were to hand over the Fire Emblem, Ylisse's national treasure, to him. Upon refusing, Gangrel threatens to pry it from Emmeryn's "cold, dead hands" and sends a single brigand to take the Emblem. Chrom instinctively kills the brigand with nary a second thought. It is in this moment that Chrom commits an act of war on Plegian soil, setting the stage for the rest of the game's events. Chrom didn't need to kill the brigand. Gangrel's threat was simply words, and a single brigand could be easily disarmed without killing him. He hadn't even attempted to strike at Emmeryn yet. But Chrom's love for his sister and his own impulsive nature singlehandedly led to a brutal campaign against Plegia. War had been declared, and it might have been avoided if Chrom had thought the situation through. Chrom is a flawed character, and because of his flaws, he must live with the fact that his actions had drastic consequences.
Eventually, Ylisse's campaign against Plegia comes to a head when Emmeryn is taken hostage by Gangrel's men to be publicly executed. In a race against time, Chrom, Robin, and the Shepherds book it to Plegia to save her. Once the battlefield is cleared, Chrom prepares to save his sister, only for an ambush to occur. Risen are summoned and shoot down the Ylissean Pegasus Knights with their arrows, eliminating Emmeryn's escape route from atop the spire. Gangrel gives Chrom an ultimatum: give up the Fire Emblem or have the Risen shoot down Emmeryn. Giving one last speech beforehand, Emmeryn spares Chrom of the sadistic choice and walks off the spire, committing suicide and preventing Chrom from giving up the Fire Emblem.
The next chapter ends with the Shepherds escaping a skirmish against Plegian forces, and upon entering the barracks once more, Robin takes it upon himself to reignite Chrom. Chrom sees himself as a failure for not preventing Emmeryn's death. He uses the word "powerless." He had no physical way of reaching her. For one time in his life, Chrom was forced to sit there and watch an atrocity transpire that he couldn't prevent. He watched as his older sister, his longtime guardian, fall to her death to spare him from a choice that would endanger Ylisse's people. Robin seeks to provide another viewpoint.
Robin:
I was powerless once too, remember? And yes, alone, I don't think either one of us is half the person your sister was. But together...maybe we can be something more. If you fall, I'll be there to pull you back up. When you fight for your sister's ideals, I'll be by your side. You don't have to become your sister, you know. You can still be true to yourself. You just have to give people hope in whatever way you can.
Chrom:
And what if I can't? What if I'm not worthy of her ideals? Robin, what if I drag you down with me?
Robin:
If you aren't worthy, you'll keep at it until you are. And if we both fall down, well, that's what friends are for, isn't it?
It's in this moment that the bond between Chrom and Robin is fully cemented, in my opinion. Chrom proclaims that he won't falter again, so long as he has the support of his tactician and his troops. And in Chrom's fated battle against Gangrel, Chrom prevails and Gangrel is slain. As the newly-crowned Exalt of Ylisse, Chrom married and had a daughter, Lucina, and vowed to bring Ylisse into an era of unparalleled peace.
Sadly, however, peace doesn't last long, as the Valmese from across the ocean have
launched warships toward Regna Ferox, Ylisse's closest political ally. Reluctantly, Chrom decides to aid Ferox in the war against Valm, as they are a threat to Ylisse as well.
The Valmese arc in Awakening is controversial, to say the least. Many fans say it was simply a filler segment. However, I disagree, as Chrom's conversations with Walhart do quite a bit to show how Chrom has grown as a leader and how he juxtaposes Walhart in his style of ruling.
During their confrontation in chapter twenty, Chrom's first reaction to facing Walhart is asking the Conqueror if he'd surrender, to which Walhart scoffs. The rest of their pre-battle conversation is as follows:
Chrom:
It did not have to be this way... You believed in mankind's strength... So did my sister. You believe that we are masters of our destinies... So do I. You could have joined with us.
Walhart:
ME, JOIN YOU?! Does a pegasus join with the flea on its back? A dragon, with a cow it eats?! You forget your place, BOY. I am the Conqueror! I will unite the world!
Chrom:
No! ...I will. And not by forcing all the people to choose the sword or the knee. Peace will only come by stoking people's hearts...not their fear.
Walhart:
You think that's what you've done? What your sister did before you? No, she shouted some nonsense and leapt off a rock! Such weakness!
Chrom:
Wrong. Not weakness—strength. That one act lives on, and WILL live on, longer than all your conquests...
Walhart:
And longer than you will... Come then, flea, and die for your peace!
Chrom:
Emm, I tried...
The weight of Emmeryn's legacy is clearly weighing on Chrom. His every action as Exalt was done with his sister in mind, as if to ask, "What would Emmeryn do?" In chapter six, he had told Robin that he would never be able to show compassion to those who did him harm, as Emmeryn did when her people turned against her. Here, however, he does just that. Walhart the Conqueror, a man who terrorized and subjugated an entire continent, fought Chrom's army with his own for the entirety of a brutal campaign, and threatened to take over Ylisse and Regna Ferox as well, was now facing off against Chrom directly. Chrom's first, instinctive reaction, however, is to ask if Walhart will stand down. And then when Chrom cannot reason with him, he reluctantly fights him, having unsuccessfully tried to use Emmeryn's own method of peace.
Until now I haven't touched too much on Chrom and Robin's relationship, despite it being a crucial component of Chrom's character. Throughout the game, Robin has acted as emotional support for Chrom. Chrom is prone to doubting himself, and Robin is always there to provide reassurance, as he did in the wake of Emmeryn's death. Likewise, Chrom places his full trust in Robin, both as commander and tactician, and two best friends. However, a revelation is uncovered. In the bad future that Lucina comes from, Robin is the one who took Chrom's life, impaling him with a hardened bolt of magic through the chest. Upon having this confirmed for her, Lucina draws her sword and prepares to kill Robin then and there, to save both her father and her future. Regardless of Robin letting her or not, Chrom comes in at the last minute to stop her, having heard every word, and reestablishes that nothing can shake his faith in Robin.
Chrom:
Robin and I have held fast through good times and ill... We swore to be two halves of a greater whole. You underestimate the strength of those ties, the bonds we share. I believe in them more than some foretold "destiny."
Lucina:
That is easier to say when you haven't seen it yourself...
Chrom:
Lucina, aren't our ties stronger here now than they were in your future? You said so yourself. In this flow of time we are bound tighter than ever, you and I. Not just as father and daughter... But as friends. We can change things—we already have...and we will again.
Chrom is convinced that because things had already changed as a result of their actions, that the bad future is preventable, and his death at Robin's hand is far from guaranteed. In spite of his trust in others not always working out, such as when the Hierophant betrayed the royal family early on, Chrom clings to his ideals. To him, they are worth fighting for, especially when his best friend depends on them. That being said, despite being trusting, Chrom is far from naïve and stupid. He recognizes that Plegia's invitation for parley will likely not end entirely hospitably. He doesn't go to Plegia without him and his men being armed. This is a big part of Chrom's character that often gets mixed up by those online. Idealism is not the same as naivety or stupidity. Chrom holds true to his core beliefs and recognizes the danger associated with them, but should he feel the need to, he will take precautions.
So in short, Chrom is a man who struggled to fight against the legacy of his warmonger father while trying to more closely emulate the ruling style of his older sister Emmeryn. He is a father to his men, and is capable and strong, if a bit reckless. Chrom acts almost solely on instinct and will defend those he cares about to the ends of the earth, and will help someone in need no matter the danger it may pose to himself. Chrom is also plagued with self-doubt, which only worsens after Emmeryn's death, until Robin's friendship breaks him of it, and the two become two halves of a greater whole.
He's also a total dork who stared slack-jawed at (his future wife) Sumia when she saved him from being turned into a pincushion, has an awesome design and color scheme, has a great voice, has an awesome sword when fully upgraded to the Exalted Falchion, and can use lances, but those are more superficial reasons why I like him, to say the least.