Because I’ve been reading colonial history about them lately, and then felt like ranting about them.

1) If he’s fat, give him a goddamn reason.

Now, it might be a good reason if he’s the kind of merchant who spends all his time in town, having invested in a ship or two, and waits for the profits to come to him. He’d have access to luxuries food there, and not much exercise. But authors usually have merchants traveling the roads, the better to meet heroes at inns and perhaps get kidnapped into a random adventure, and those merchants are fat anyway.
Why? Why would someone who had to walk trails, ride horses, haul wagons out of muck, defend his own life (and the profits) when the odds were against him, haul heavy chests in and out of wagons, and penetrate dangerous territory be fat? He wouldn’t have as much incentive to be as the merchant who just stays in town, and he wouldn’t have access to good food either, at least if the author is telling the truth about the usual standard of meals at fantasy inns.
The usual explanation for this is that the merchants do nothing but sit in the wagons all day, and the guards are actually the ones who defend their lives and treasure and do all the heavy work. Now, if he’s also greedy (point 2!) wouldn’t he want to make sure that his treasure has the best protection possible? Yet all the guards seem to be the kind who run away at the drop of a hat, or get taken by bandits, or can’t fight worth a damn. I’d think the merchant wouldn’t be that adverse to learning to grab a sword and fight once in a damn while. And if he’s young and just starting out, where would he have the money to hire all the guards, hmmm? And if he’s old and been on the roads for a while, why wouldn’t he be a better judge of character and hire better guards?
Authors seem to make merchants fat merely to laugh at them. Because, of course, laughing at obese characters is always funny.

2) Why is he greedy if he’s just making a living?

There’s a true double-standard for merchants as compared to other fantasy characters who manage to acquire money or treasure. If adventurers raid an underground tomb, or kill a dragon and make off with its hoard, they earned it through their courage and cunning. If the feisty princess faces up to the Dark Lord and afterwards is honored and given a yearly pension and a house, she earned it by what she did. If a thief steals something precious, why, she’s just as clever as all get out, and deserves to be able to keep the bauble without its owner wanting it back.
But a merchant who makes money is Evil. Especially watch out for him if he wears gold chains, or rings, or fine clothes. Because wanting to look nice, even if it’s because looking nice will convince your customers to part with more, is REALLY Evil.
Hello, stupidity. I suppose the prejudice against merchants in fantasy might carry over from a prejudice against businessmen in our world, but it’s still stupid, particularly when the author makes it clear that she has no problem with money or possessiveness over it; she just has a problem when the money is in the hands of merchants. There’s also an underlying tone that the merchant didn’t do enough to earn the money, unlike the adventurers or the feisty princess or even the thief, so he doesn’t deserve to have it.
If the merchant is traveling unexplored territory to expand his market, he’s going to have hardships to rival those of any adventurer, who mostly travel very familiar ground looking to do great deeds. He’s going to be worse off than the feisty princess, who miraculously does manage to sleep in an inn a great deal of the time, or a thief amid a large and competent party. He’ll be surrounded by bad weather, unexplored ground that might turn to quicksand or lead into a swamp (forcing him to backtrack tens or perhaps dozens of miles), probably hostile natives who might not speak his language, companions who might desert if they become convinced the venture isn’t going to pay off, the pressure of making a profit so that whoever backs him, or he himself, won’t lose money, worry over the safety of the goods he’s dragging along, worry over the health of the animals, lack of food, poor sleeping conditions, lack of shelter… On and on it goes. There’s no lack of courage there. The idea runs that wanting to make a living without swinging a sword is evil, um, somehow. It melts when you look at it, but a lot of fantasy authors don’t bother to look at it.
If the merchant is traveling familiar territory, it’s still probably dangerous and hostile and violent. If the journey is long, he could still face many of the problems mentioned above. It’s if not, there’s probably fierce competition and perhaps bandits, and there’s always the chance that a more mundane problem, like a wagon getting stuck in mud or a pestilence among the horses, could delay him, and maybe spoil his produce.
Merchants can be just as exciting and ruthless and strong as other characters “Fat” and “greedy” are only stereotypes, not the truth.
3) Understand how merchants fit into the economic system of your world.
If their caravans are the only methods of supplying some desperately needed goods, they’ll be watched for and treasured. People may still resent them for the high prices they’ll drive, but merchants wouldn’t be objects of general contempt to their faces, they way that they are in a lot of fantasy books. Highwaymen trying to rob them would be likely to take the goods as well as the treasure, not demand coin and slit their throats if they didn’t have any. For one thing, then the merchants would stop coming that way. For another, highwaymen that ruthless and persistent would draw the military after them, not just merchant guards.
If these are high-seas merchants whose travels link distant ports, they’re likely to be even more treasured, and to get money for carrying the goods as well as for selling them. Remember that the ships will carry the necessities of life and gossip from distant lands as well as whatever luxury items they might bring in. Once again, any abuse is likely to be because of prices, not the general fantasy fighter attitude of, [spit] “Oh, you’re a merchant, are you?”
If the merchants are fairly common and in close competition, say in a market square, they’ll put up patter to draw customers and try to make sure that their goods are the ones worth buying. That means not acting all superior to customers, because anyone might be the one person who comes over only intending to buy a cloth and then gets drawn to pots and pans and whole blankets by the merchant’s skillful chatter. The customers could say the merchant is greedy and stupid, and he might nod along, as long as he gets to sell something. And if he does, who has the last laugh, hmm?
If the merchant is operating out of a shop, the customer has to come to him, and he’s more likely to be a settled and established sort of fellow. Any customer who wants a piece of jewelry appraised, wants to buy an expensive book, or wants some other object or task done that requires a lot of money is likely to get an unfair price from the merchant. Maybe the customs of the world allow for haggling and some good-natured complaining, maybe not, but the merchant is unlikely to be the kind of person who would melt for puppy-dog eyes or sell the object for a lower price just because the person begged him for it. And I for one am sick of the scene where something like this happens:

Emilee lowered her eyes. The magical amulet that her mama needed to get well cost far more than the three copper coins she had in her hand. “I’m sor-sorry,” she whispered. “I’ll go now.” She turned for the door.
“Wait, child.” The shopkeeper hurried after her, and pressed the amulet into her hand. Emilee turned and stared up at him in astonishment.
“Never tell anyone I gave this to you,” said the merchant, and then turned and hurried back into the shop, muttering something about “bad for business.” Emilee wiped her tears away and gave his back a brilliant smile. She knew the truth about him, even if no one else did.

Gag, gag, ick. It’s measuring how good a person the merchant is in terms of kindness to the main character. If you’d balk at doing that when the secondary character is a mage or a fighter or someone else, why not when it’s merchant? He has a life of his own, too, and the amulet he gives away might mean the difference between a nice meal and a poor one for his own family. (And if you are the kind of author who does something like that for every character…um, well, don’t let me read those scenes).

4) Consider his relations with different classes.

Does he suck up to aristocrats? He might have to, if he’s part of an emerging middle class that wants the privileges and status of aristocracy, but is disdained as “new money.” On the other hand, perhaps the middle class has different priorities, or the merchant himself does, or the aristocrats in this world never had a disdain for trade. The relationship between merchants and any upper class in the story doesn’t have to be foreordained.
To equals, it might go back to the economic relationships again, as well as what exactly he does. Does he compete with other merchants to travel certain safe routes and sell to certain prosperous customers? Then the competition might be cutthroat. Or maybe he has a child married into one of those families, or married into them himself, or the trade networks rely on some different mechanism than only one merchant or family controlling them. He could have partnerships, rivalries that aren’t cutthroat, friends, nodding acquaintances, and so on. It relies, as most character development like this does, on considering the merchant as a person with an inner life of his own, rather than just a stock character to appear and make nasty comments about the hero, or stand in a crowd and helplessly wring his hands.
To lower classes, he might be any mixture of arrogant, condescending, standoffish, understanding, mild, generous with credit, tightening the noose if the person looks unready to pay up, and so on. Consider his life here. If he rose out of the underclass himself, he might rightly feel that he can trust no one there; he might just as rightly feel confident with some people he knew in his youth. If he’s always been an owner of a shop, inheriting it, then he might have no good experiences with people who wander in and try to rob his shop after hours, and wouldn’t hesitate to turn Miss Spunky Young Thief over to the city watch. Understandable, all of it, not desperately wrong just because Miss Spunky Young Thief happens to be your heroine.

5) Merchants can make excellent background families for your heroes.

Middle-class heroes are very, very rare in fantasy. Most are either nobility, peasants, or people who think they’re peasants and then turn out to be royalty (stab stab die die.) If they’re not very poor, their families still usually farm, or mend pots, or that kind of thing. Where are all the cheese-sellers’ sons, the jewelry appraisers’ daughters, the children who grew up in a shop and so might have a credible chance of being familiar with faraway strangers, languages, and objects? Almost nowhere to be found. Most fantasy authors seem as ashamed of them as the aristocracy is usually portrayed to be.
There’s nothing inherently wrong with having a different kind of family background, although of course it won’t inherently improve a story either. But it has some advantages that the upper-class and lower-class backgrounds don’t:

  • heroes might have learned to read and write for eminently practical reasons, instead of having to learn from Wise Old Mentors or “found” books as peasant heroes usually do.
  • heroes can have the experience of dwelling in cities without having to be thieves and falling into all those stereotypes (see thief rant).
  • if their families travel, there’s a way to see the world and know something about it, so that they aren’t the stereotypical ignorant teenagers who just tear off into the world without knowledge.
  • there’s no fighting against the stupid idea of not wanting to be a lady or a lord, with the risk of turning every other character in the immediate area into a stereotype (oftentimes it seems like the only “good” aristocracy in fantasy books are the ones who don’t care about luxuries, even as they wear or eat or use them).
  • heroes could meet strangers relatively easily, without a contrived setup.
  • heroes might well have a reason to want to leave home; it really could be too boring, if they have no interest in the business that consumes the family life, and they could possibly not leave their family in the lurch, the way that a peasant boy would if he ran off from a farm that needed every single pair of hands to do the work.

I’m sure you can think of more.
*puts up ‘Merchants Are People Too’ sign*