Be As You Are-Not As I Wish You To Be
I have a confession to make: I have very little tolerance for most modern fiction. Characters are either too perfect, with only a few charming quirks, or deliberately designed to be villainized. (Tragic or otherwise.) This works for juvenile tales, no disrespect to the term 'juvenile', I mean it in the most literal sense, but when it comes to adult fiction, I often find myself embarrassed by the lack of ethical depth and emotional range in characters.
I believe that conceptualizing a character is a lot like meeting someone new. There are the things you've heard about them, (heresay) your first impressions, (limited interaction bias) and all the assumptions that go along with those elements. The majority of the time, a stranger's true 'character' is a combination of many other things, and a good number of our assumptions and biases are usually wrong. When I'm writing these characters, I want them to show me who they are, not who I think they are, or who I want them to be. That requires tolerance and open mindedness, and as ridiculous as it might sound, it's good practice for me. This is how I want to treat non-fictional people, as much as possible. That's a work in progress, as well, but I digress. This isn't some deep point I'm trying to make. All humans are morally gray, whether they want to admit it or not, and our hard lines, principals and tolerances vary wildly. But in the end, that might be what makes us most human, and I would like to give that opportunity to my fictional characters, even if I end up loathing them.
Besides, you don't have to like someone in order to love them.