Sympathy
Of course, if you write movies, the creation of sympathetic characters is one of your primary jobs. At least if you're writing in the commercial realm. When first approaching characters - I'm talking early drafts - this can be a pretty big challenge for me personally. A lot goes into the creation of a primary character - what do they want, what are their flaws, what inside the person can the audience identify with...is the character sympathetic or not? In the end, the big question, the one Kubrick "taught" me to ask about all things movie related is...is it true and is it interesting? Often, I find that the thing I initially concentrate on is making the character interesting. This can be defined in all sorts of ways - different things interest different people - but contrast and its sharper cousin conflict are two things I'm drawn to. The result is that there are times, early on, when my primary characters are interesting but not sympathetic. Which brings me to a fairly important question - what makes a character sympathetic?
If you think about it, we all like different people. We all have different friends. My best friend could be your worst enemy and vice versa. We've all met a friend of a friend at some point in our lives and thought, "I don't see how the hell anyone can be friends with that guy." So a singular definition of sympathy is not something we commonly hold. I think the actor goes incredibly far in this department when it comes to movies - rarely does anyone reading a script acknowledge as much, however. But you can see where I'm going...this is where creating characters gets complicated. There's no formula for sympathy. The trick is to create a character who's likable/identifiable but not a paper thin stick figure. Personally, I think it's easiest to make a character as interesting as possible and then worry about making him sympathetic because sympathy can be created via smaller changes.
A good example of this is the character of "Grant," the protagonist in our screenplay THE SURFACE. In early drafts, Grant was admittedly a prick who refused to commit to his long-term girlfriend because he believed doing so would take all of the potential and excitement out of life. In later drafts Grant is still a prick who refuses to commit to his long-term girlfriend BUT we see him acknowledge that he may be wrong - and we even got the sense that he'd like to try to change. I believe it was this small revision that made him sympathetic (if you've read the script, this is all about the coffee table sequence in the first act).
It's interesting how small changes can make a big difference - especially when it comes to character.