Fighters. They're one of the most straightforward classes in fantasy RPGs. If you're not sure who the fighter is, just look for the guy with a sword in one hand and a shield in the other, barking orders and taking the fight to the monsters. While that image is iconic, it also misses a lot of the potential of the class. Worse, the stereotypical fighter is a character with no background, and no interests, off the battlefield. For all intents and purposes, the party may as well be traveling with an enchanted suit of plate armor that rolls initiative from time to time.
How do you make fighters stand out, though? Well, you can start by going down this list. You might also find the article 10 Background for Your Martial Characters to be particularly useful, if you're looking for a starting place to flesh out your PC.
#1: What's your style?
Fighters fight. After all, it's right there in the name. But with so many different options on the table, you need to narrow down your character's specialty. So, what about your fighter? How do they fight? What's their weapon of choice? Do they have a fighting style?
Weapon and fighting preferences can make a big difference in what kinds of skirmishes you're best in, but those choices can also say a lot about who your character is. The post "What Does The Weapon Say About The Warrior?" provides some solid insight on this point. For example, is your fighter used to being part of a shield wall? Do they excel in small unit tactics? Are they more of a duelist? Are they an archer, a spearman, a mounted charger, or a bare-knuckle brawler? Each of those specialties can say something about who the character is, and how they do their job.
#2: Who taught you how to fight?
Fighters come in all shapes and sizes, but the one thing they share is every one of them had to have a teacher in some way, shape, or form. Maybe your fighter was taken as a page at a young age, and schooled in the knightly arts. Perhaps they grew up on the wrong side of town, where fighting was just part of the daily struggle. Maybe your fighter joined the army, or the local militia, and was schooled by ex-adventurers. They might even be an athlete, who worked with an experienced coach to become the pinnacle of their sport.
Once you know what your fighter's style is, and how they learned it, ask if anything about that style would be recognized by those familiar with it. Do you plant you pike in a particular way, which immediately tells someone you were an imperial regular? Do you one-hand a bastard sword the same way as your father, the infamous arena champion Grattis the Iron Knight? Is your footwork reminiscent of the storm soul duelists, who can strike so fast even their opponents don't realize they're dead? Or do you use the signature kris-bladed knife infamous among the Rough Boys gang in the Crumbling City?
These little hints are great for showing your backstory rather than telling it. By describing the actions, and asking other players for Knowledge checks, they can catch details about your character in the heat of battle, or while giving them a once-over during that first meeting. It's more organic, and a lot more fun, than having long, drawn-out, "So, here's my character history," session round the inn table.
#3: Why do you fight?
Again, fighters fight. Whether you're an archer or a tank, a halberd-bearer or a warhammer wielder, your class features are built around making you a solid combatant. You can dish out punishment, and take more than your fair share.
But why do you fight?
Are you a mercenary, just trying to make an honest living using the skills you have? Do you fight for your ego, trying to make your name known far and wide as a great warrior? Do you fight to protect yourself, your friends, and your family? Do you fight out of patriotism, to defend your nation? Do you hope that, simply by being present and willing to fight, that others will choose to solve problems without violence? Or do you fight because, deep down, there is a savage thing inside you that craves the heart-pounding rush of battle?
#4: How do you feel about fighting?
So, you know how your character fights, you know where they learned their skills, and you've got a pretty good idea what motivates them. But how do they feel about fighting?
As an example, take Koralinn Grands. The middle child of nobility, she resented not being allowed to take up the sword and arms of her family to become a knight. So she trained with the squires in secret, becoming a formidable foe. She abandoned her noble family, and went out into the world to prove herself. She survived her first battle, but the dead, lifeless eyes of the companions she knew, and the strangers she didn't, still haunt her memories. She knows there is no erasing the blood on her hands, and that she can never put down the weight of the dead. That's why she tries to use her words, rather than her blade, whenever she can.
From the other side of the spectrum, you have Dagoth "Breaker" Hornswall. The son of a butcher, he was born big and grew bigger. When the militia began recruiting, he found that his skill with a blade was in quite a demand. He preferred the mace, though. It felt more like the ox-killing mallet in his hands. Despite the shattered messes of bone, blood, and brains he leaves behind him on the battlefield, splitting a skull, or caving in a ribcage troubles Dagoth no more now than it did in the slaughterhouse. He doesn't seek out trouble, and he takes no special relish in his work, but when the order comes to swing he never so much as hesitates.
#5: Who are you, other than a fighter?
We tend to get caught up in the mechanical applications of our characters. Rogues steal and back stab, wizards cast arcane spells, druids cast nature spells, paladins smite evil, etc., etc. And, again, fighters gonna fight. It's what their features are focused on, no matter which archetype you use.
But what else is there to your character, besides being a fighter?
Because yes, Darne Von Hendren is one of the deadliest duelists who has ever graced the red circle. However, he also likes kittens and has a soft spot for orphans. Araine Meerden is a leather-lunged sergeant in the cavalry, but she also enjoys horse races; riding or spectating, it's all the same to her. Pressen Marks may not have the eyes he used to have, but he can still split a hair at a hundred yards, and he likes to spend his time tutoring the next generation of archers. Because sooner or later, he knows someone will have to take his place.
Your character can fight. But what else do they do? Do they have social skills? Do they know the local layout? Do they have underworld contacts? Are they part of the aristocracy? Who are they, behind the armor?
"What Does Your Character Do When Not Adventuring?" makes for good supplemental reading, if you need some inspiration for this part.