Bringing characters to life is how the writer brings a story to life. No one walks into a story out of nowhere; no one enters a scene without baggage. No scene sizzles without believable and heart-grabbing characters.

General

Every character needs to catch the imagination and spark the reader's desire to know more, to see how the character will interact with the world, and react to events and other characters. Every character must make the reader respond emotionally and even  minor characters need some development, to be more than cardboard cutouts;  even a po-faced nebish can appeal to readers.

Here's a list of some elements that add to character-appeal and increase dimension:

back-story: where did he/she come from; how did he/she end up here?

physical attributes: size, build, looks, etc.

style: clothing, accessories and accoutrements; grooming

stuff: what's in the purse?

mannerisms: behavioral and speaking

virtues and flaws

values, beliefs, opinions, sense of humor; rich or poor?

relatives and relationships: loner or gregarious?

Dimension

Even though they may not come directly into the story, you, the writer, need to know these specifics so that you can present the character with the nuances that are part of all human realities. (In other articles we'll go into the particular demands of creating believable characters with non-human realities.)  It is the subtle touches that give your characters true believability.  It is the wealth of subtleties that give your characters depth.  It is the subtlety with which you reveal them that makes them effective.

While many elements create a character, it is also important to salt them into the story, spread them around, reveal them gradually.  Unskilled writers stack adjectives way too much, and so distract from action and the story.

Emotional Appeal

Love or hate, admire or despise:  the important thing is that the reader cares about a character.  Build sympathy with the foibles and circumstances common to us all; play the pathos card, if this character should be appreciated as a dupe of fortune, a put-upon victim; show him/her doing despicable things and make the reader cringe and despise.

Virtues and flaws come in every human package, and arouse some kind of emotional response--though not always what seems logical or predictable.  Your characters own reactions to others will reveal him/her vividly. Not all at once, but so the reader's awareness and emotional response grows over time.

Relationships

Every character interacts with other characters, that is what provides the action and conflict in a story.  When you create your characters, and throw them together, there must be sparks:  In a sense, every relationship is also a complex “character” in the story.  It is essential to weave such interactions together with due regard for what has been established with each character.

Character-sourcing

When you base a character on yourself, there is a special problem: your own self-image, and what you want people to see in you, and more to the point, what you might not want them to see.  Failing to meet this challenge head-on results in characters that are too nice to be interesting, or too whiny, too self-justifying, too misunderstood and victimized. Or maybe too heroic, too powerful, too right all the time, too wise.  This all comes back to that question of why you write in the first place.

When you base a character on someone you know, you may be thinking of how they will feel when they read how you see them, and so that character may come out stilted and flat and unrealistically nice--or nasty, depending on your own relationship with the person you have in mind.  This requires another kind of confrontation with your own feelings.

A solution is to fill in that character with elements not at all like the real person in question, let the character be the character.  Draw on what you know, and who you know, but create for the story, not for your personal fantasy or feelings.

There is no character without both broad characteristics and nuance.  There is no story without characters.  Make them sizzle, make them outrageous, make them memorable and complex, and they will make the story!