back to Dexter in "Winter Dreams," let's see what makes him a dynamic character by examining his character traits near the beginning of the story versus toward the end.

How he is near the beginning of the story:

As a young teenager working as a caddy at the golf course, Dexter is hardworking and competent: he never loses a ball, and his boss calls him "the best caddy in the club." Although the narrator doesn't explicitly say so, we believe Dexter has been doing this job for quite a while, so we assume he's also reliable. At the same time, he's deeply affected by the changing of the seasons and is often overcome by melancholy. We can tell how deeply emotional he is, too, because he reacts so impetuously to meeting Judy for the first time, suddenly throwing away his caddy job:

"But he had received a strong emotional shock, and his perturbation required a violent and immediate outlet."

And, notably, Dexter describes himself as a boy as "proud" and "desirous." The narrator adds that Dexter operated under the illusion that Judy was desirable, so we also know that Dexter was easily enchanted, or full of illusions.

As the story goes on, Dexter grows up, becomes successful in business, plays golf, and suffers endlessly from his on-again, off-again relationship with Judy. Because he wants to possess beautiful things, he keeps on chasing after the beautiful Judy no matter how many times she hurts him.

Now let's take a look at how he is at the end of the story, as a result of all those life experiences:

Is Dexter still hardworking, competent, and reliable? Yes. He's one of the richest young men in the country, it seems, and he's worked his way into a higher social class. So, that aspect of his personality hasn't changed.

Is he still melancholy and impetuous, given to fits of sadness and sudden emotional displays? Yes. Look at that scene toward the end with Devlin, when Dexter loses his cool when he hears what happened to Judy.

Is Dexter still enchanted? Is he still blinded by illusions? No. He has lost his illusions; he understands the reality now that Judy is not some perfect, ever-gorgeous being. She's become a frumpy housewife and isn't even pretty anymore. Dexter realizes this, and then he realizes that he's become disillusioned, finally. That's how Dexter changes. Here's how he acknowledges and laments that major change:

"Long ago," he said, "long ago, there was something in me, but now that thing is gone. Now that thing is gone, that thing is gone. I cannot cry. I cannot care. That thing will come back no more."

To sum it up, although Dexter retains many of his basic personality traits, his life experiences cause him to build up and then shatter his own illusions. His way of looking at the world changes from enchanted (and unrealistic) to realistic. That's how he changes, and that's why he's a dynamic character.

In “Winter Dreams” by F. Scott Fitzgerald, Dexter Green is a static character. As a static character, he remains steadfast in his pursuit of material wealth and Judith Jones.  

Although he ages from a teenager to an adult in the story, he does not waiver in his core persona. As a teen he dreams of accumulating wealth so he can enjoy the prestige of belonging to the golf club on Sherry Island, where he caddied in his youth. He wanted to prove to the club members he deserved to be one of them.

October filled him with hope which November raised to a sort of ecstatic triumph, and in this mood the fleeting brilliant impressions of the summer at Sherry Island were ready grist to his mill. He became a golf champion and defeated Mr. T. A. Hedrick in a marvellous match played a hundred times over the fairways of his imagination, a match each detail of which he changed about untiringly--sometimes he won with almost laughable ease, sometimes he came up magnificently from behind.

The day he witnessed the antics of the young Judith Jones at the club, he set his sights on making these dreams a reality. From that day forward he strove to accomplish his goals by going to a prestigious college, establishing a successful dry cleaning business, and surrounding himself with the people he wanted to emulate.

He made money. It was rather amazing. After college he went to the city from which Black Bear Lake draws its wealthy patrons.

It only took Dexter a few years to make a name for himself. The men of the club wanted him to join them, and he did. This was the same day he became reacquainted with Judith Jones, who had become a beautiful young woman, and his quest to be with her began in earnest.

When he was twenty-three Mr. Hart--one of the gray-haired men who like to say "Now there's a boy"--gave him a guest card to the Sherry Island Golf Club for a week-end. So he signed his name one day on the register, and that afternoon played golf in a foursome with Mr. Hart and Mr. Sandwood and Mr. T. A. Hedrick.

Throughout his young adult life, he pursued a relationship with the fickle Judith Jones, who drifted in and out of his life. Judith appeared at inopportune times, and Dexter even gave up the chance to marry a solid, wealthy young woman to have a fling with Judith.

But F. Scott Fitzgerald speaks to the reader before the story concludes.

THIS STORY is not his biography, remember, although things creep into it which have nothing to do with those dreams he had when he was young. We are almost done with them and with him now.

The war intervened and years later, Dexter, a successful businessman who no longer lived in the mid-west, held his dreams intact. It is not until an acquaintance brings him news of the demise of Judith’s beauty due to a difficult marriage that the reader witnesses the death of Dexter’s dreams.

Dexter Green changes in several very significant ways in the story. As a boy, he lives a working-class life in a working-class community, one that provides services for the wealthy people who live and play on Sherry Island across the lake from Dexter's home. Dexter has very little money, but he dreams of a life of wealth and glamour--the kind of life he observes among the rich people he sometimes works for.

By struggling to get an education at "classy" university (not a state college), Dexter further observes the wealthy upper class and patterns himself after the way these people dress, speak, and behave. He starts a business, builds it into a chain, and sells out, earning himself a great deal of money. As a rich young man, Dexter now moves in the social circles he once admired as an outsider. He has come a long way from the poor boy he used to be.

These are important changes in Dexter's lifestyle, but the most significant change in his character occurs through his love affair with Judy Jones. Dexter loses Judy, who represents for him every dream he ever had, but he keeps her memory in his heart and continues to live on it. When his memory of Judy is taken away from him in the story's conclusion, Dexter is robbed of his illusions, and he mourns their loss:

Even the grief he could have borne was left behind in the country of illusion, of youth, of the richness of life, where his winter dreams had flourished.

"Long ago," he said, "long ago, there was something in me, but now that thing is gone. Now that thing is gone, that thing is gone. I cannot cry. I cannot care. That thing will come back no more.

Reality has replaced romance in Dexter's life, and he will no longer be able to lose himself in his dreams. 

Dexter's characterization throughout the story largely depends on his thoughts and emotions, not on his physical appearance. But we know for certain that he dresses well, and we can infer that he's physically fit and reasonably handsome.

Throughout Parts I and II of the story, we get very little physical description of Dexter aside from the narrator's descriptions of his motions, like when he stands still in awe of Judy, or like when he stretches out on his springboard in his bathing suit after swimming. (We're practically deluged with physical descriptions of Judy, though!) The fact that Dexter is a very capable caddy as a teenager, then a capable golfer as a young adult, does suggest that he has some degree of physical fitness.

However, Part III provides this image of Dexter:

He knew the sort of men they were--the men who when he first went to college had entered from the great prep schools with graceful clothes and the deep tan of healthy summers. He had seen that, in one sense, he was better than these men. He was newer and stronger. Yet in acknowledging to himself that he wished his children to be like them he was admitting that he was but the rough, strong stuff from which they eternally sprang.

From the information above, you can infer that although Dexter isn't quite as good-looking or tan as Judy's other boyfriends, he's still fit and strong. We also find out that Dexter dresses very sharply:

When the time had come for him to wear good clothes, he had known who were the best tailors in America, and the best tailors in America had made him the suit he wore this evening.

Later, in Part IV of the story, Judy comments on Dexter's appearance:

"You're handsomer than you used to be," she said thoughtfully. "Dexter, you have the most rememberable eyes."

Although it makes sense that Judy would only associate with handsome men, meaning Dexter must be handsome, we also can't put much faith in her words. She often says what she doesn't mean, and she's very manipulative.