Hmmmm… for me, the answer depends partly on what type of story I’m telling at the moment.
Part of the reason is because I feel that every genre and medium has its own particular character stereotypes and ways that have already been done to death as far as making a character sympathetic.
Like, for example, the detective with a drinking problem or broken marriage, or the geek being bullied or who wants to go to the prom with the cheerleading queen or the housewife with the overbearing husband and self-centered, barely controllable kids who take her for granted.
Since these have been used so often, we have to create new characters that a reader will be able to sympathize with, identify with and find interesting enough to follow to the story’s end.
So, as an example, instead of an alcohol-ridden divorced detective, I might make him a teetotaler (non-drinker) who the other patrolmen can’t stand because since he doesn’t participate in their nightly after-work revelries (and also because the Captain loves him), they think he’s a stuck up asshole kiss-ass.
And he’s raising a kid with Down’s syndrome alone because the mother, whom he met and “knew” after a night out at the bar, couldn’t handle it and blamed him for sleeping with her that one night and causing this child to come about and she generally blamed him for ruining her life and so she split soon after the baby was born.
Or the teen is a geek, a true whiz and genius but he’s not a socially inept outcast. In fact everybody likes him. He’s a pretty average guy who uses comedy to get people to like him and it works except that’s part of the problem.
Girls only “like” him. He suffers from the “Buddy Syndrome” - where girls only like him as a friend and don’t see him as boyfriend material or feel sexual desire towards him. Not only that but his heart burns for the goth chick who HATES everything and anything normal. And he’s about as normal as they come- but he can’t help his attraction to her. He must have her!
I also think it’s important that there be a symbiosis between the two: the character and the story. They have to complement each other. Twist the character and often, the new character will add even more conflict and drama to the story.
By this I mean: let’s say you have a mystery. Well, make the detective in love with a high school goth. Or make the geek have to solve the murder. Etc.
Overall though, I think, the most important thing is to create characters that a reader can SYMPATHIZE with, IDENTIFY with and ADMIRE or find INTERESTING enough to follow.
If you can evoke these three things, you should have a pretty good character.
SYMPATHIZE:
One way to get the reader to sympathize with the protagonist is to show them as the underdog or having to face adversity in some manner. Whether it’s an asshole boss at work, a bad home situation, her having a bad hair day, being late for a job interview, they’re an orphan etc.
Another way to get the reader to sympathize is with a flaw.
Alcohol, depression, drugs, self-loathing, any kind of crutch. It shows the character is human - BUT it’s important to somehow show the reasons why the character is like this, so the reader can sympathize. You don’t want the reader to be contemptuous of your character.
ADMIRE, BE EFFECTIVE
One of the most important things is to not make the character ineffectual. They have to be effective. They have to be able to take action and propel your story forward.
The reader has to subconsciously admire your character, be willing to follow them.
One way is with a “Pet the dog” moment. Where the protag does something kind and admirable. Sticks up for an underdog. Sticks to their principles against material gain. Fights the good fight against all odds. Follows their dream. Something the reader will admire.
Another effective way is to show the protag as especially good at something. Either their job or even a hobby. If you show them excelling at something, anything – readers will subconsciously admire that about them and it will add to their attraction.
Make them interesting. They get the best lines, do wild and outrageous things. They act like someone you’d see at a party or something and say “Wow – check that person out. They’re… different.”
You can also show that they’re cool or interesting through other’s reactions to them. If other people treat them with respect, the reader will take the cue that this person is worthy of respect etc.
IDENTIFY:
To get the reader to identify with your protag, you have to have them do things others will be able to recognize and identify with. Some of my favorite characters have been the ones who’ve caused me to sit up and say: “A-ha! I’ve done that! I’ve been there, brother!”
It can be something basic like showing a facet of everyday life, but I think the most poignant ones are the ones the writer pulled from deep down within themselves.
Those embarassing moments you wouldn’t even think of revealing face-to-face can make your protagonist seem so real.
That time you walked around with a glop of food on your chest.
Or the time you told a girl how you really felt and she laughed.
Or the emptiness and the inevitable questions you asked yourself after that 20th rejection letter.
Or walking in on your parents having sex and how it grossed you out so much.
Or the time you slept with that girl and then avoided her for weeks afterwards and didn’t answer her calls and felt like such shit afterwards.
Or the time you thought you were pregnant and couldn’t eat and were a total wreck.
I think you have to dig down deep within you. That’s where you’ll find the hidden well to dip from. The one that will make your characters resonate with others.
Because when they read them, they’ll see that they’re human – just like them. With all the good and bad parts we all have within ourselves. And that will make them believeable.