Attraction

Why are so many characters in fiction attractive? You only have to look at the word attractive and you'll know.

Writers write about attractive characters because they attract. They attract readers, and they attract the authors themselves. Authors don't generally have an immunity to beautiful people (although some will sneer and believe that beautiful people have easy success or that a beautiful person is always vain, etc.) While conceiving a character concept, especially when generating a love interest, they'll reach for that low-hanging fruit. Although not everyone finds the same things sexy, there are characteristics that most people reliably find attractive. Muscular characters suggest strength and stamina. Long hair has been a symbol of virility and an object of envy since ancient times. Strong chins, clear eyes, perfect skin, physical symmetry, upright posture, smoothness that suggests a healthy layer of fat without hiding too much of that coveted symbol of power, muscle ... these are symbols of perfect health and suggest genetic fitness.

But a character doesn't have to be beautiful to be attractive.

Chicks dig scars because scars imply strength and good survival traits. They also lend a sense of danger or imply that the person engages in risky behavior, which suggests a wild and uninhibited nature. Such a person might not necessarily be ideal for a stabile home life, but they could be passionate lovers, intimidating protector figures, and they might be wiser and more fit than someone who has never tested their limits to the point of failure.

Certain expressions of intelligence are very attractive. Knowledge of other languages or cultures suggests worldliness and self-reliance. Engineering skills can represent good planning, measuring, estimation, and thoughtfulness, all good things in a mate. Many skilled crafts are extremely attractive, and quite a few of the cliche lover-trades (blacksmith, for example) combine strength with a sensitive eye and long practice. Extended practice at anything difficult requires loyalty and devotion, which might be bestowed upon a lover. Even if it isn't, the suggestion is that there will be a level of care and attention to detail that might extend into sex and maintenance of a relationship.

Above-average height and weight can be powerful symbols of strength, intimidation power and success while simultaneously suggesting an appealing softness and heat. Weight has lost some of its glamour as the poorest members of society have gone from skeletally unhealthy to sugar drink (my mom calls pop hummingbird food for a reason) and factory processed food health problems. But a careful writer can still appropriate the traces of remaining admiration for certain kinds of fatness if they tap the source and head-off the negative stereotypes associated with fatness such as lack of hygiene, low intelligence, slowness, laziness, and lack of discipline. How? As writers always have, by showing the character engaging life with intelligence, nimbleness, discipline, etc. and describing them in appeal terms in regard to their physical traits including scent and strength.

I can go on, but by now hopefully it has become clear that in order to make a character attractive, you don't have to make them into some sort of supermodel cardboard cutout. In fact, some of the most attractive traits in a human being are their ability to provide and care for others. Students of writing know this and utilize this by revealing charitable, courageous, self-sacrificing or other kinds of behavior to show how good a character is. We care about people who care about others and who contribute to society rather than leech off of it.

Besides, fashions come and go, markers of health change from lean to fat to skeletal to huge, or muscle-bound to super-flexible, but the core traits that make humans appealing, like the capability to think, protect, act with decisiveness, care about others, and to weather adversity mentally, emotionally and physically, haven't changed and probably never will.