What makes a good story? Some may argue that the plot is the best part, others the theme, and those named Michael Bay will probably say unnecessary explosions. Personally, I tend to think the characters are the most crucial component. Without characters where is the meat of the story? Sure, plots are important as well as they set what the character's goals are, but I don't honestly think anyone will care whether or not all of humanity is saved if all your characters are area bunch of mindless drones.
This leads to the question of what is crucial to making a good character. And honestly there could be all sorts of answers, their personality, their redeemable qualities, the color of their eyes, etc.... however, I tend to think that he big key to creating fun, likeable, characters is how their development is handled, for without character development the characters themselves wouldn't feel like real people and that's the whole point of characters right? We get so much more emotionally invested in them as we get to learn new things about them along the way.
However, I've found some assumptions about character development to be rather unrealistic. It's usually assumed that there's only one type of character growth. The kind where the character subtly becomes a better person or we learn better things about them along the way, and while this development is all well and good, life isn't always like that.
Not everyone in life honestly gets better. Sometimes people get sharper rather then softer, mean instead of nice.
Many fans of The West Wing were disappointed in how Joshua Lyman's character was handled in the last few seasons. We had grown quite attatched to the funny hot headed deputy chief of staff and so were quite disappointed when he became mean and stuck up. After living off of caffeine an 2 hours of sleep every day for the past sixish years it was only a matter of time before he snapped.
There's nothing beautiful or glorious about it, but it's pretty darn realistic. Sometimes life hands you lemons and instead of making lemonade you just want to squirt them in someone's eyes. That's realistic and it's life