The most important thing to create a likable character is growth, giving them flaws and relatability. The rest will follow once you have that.
We, as readers, tend to like characters we relate to in so many ways. For example, its always good to combine characteristics than just focus on one. For example, if you make a purely innocent character, people may tend to disconnect the same as pure evil characters. You have to balance the good and bad to make them realistic and believable.
(Important to give them actual reasons for being the way they are) Naive because they've never been betrayed. Hateful because they've seen the worst in people.
I'll place myself as an example as a reader. I hate characters that represent pure goodness. Like the man is killing your friends, yet you won't hurt him? That to me isn't relatable and makes me dislike the character. Perhaps it's a virtue to be a saint, but to me, it seems like a coward hiding behind his words of goodness.
So, for me, a character has to have both good and bad for me to like them. But it's all preference. Some people love the virtuous innocent characters that watch their friends being slaughtered.
"I can't hurt him because I'm a hero!"
This type of character can be given growth, too. One who sees the world as grey instead of white and black. Or better yet, the virtuous character who sees themselves become a villain in the end.
Just write and write and you'll end up with a character that everyone loves or hates. The important thing is you evoke emotions in the reader. That is your goal.
. I prefer for the supporting characters to have that characteristic.
