Like everyone I've ever met, I have favourites. There are some people I like more than others. It might be their sense of humour, their enthusiasm, their curiosity, the warm energy they emit. Similarly, there are people I struggle with. It's a useful exercise, to work with those uncomfortable feelings and find out what that person has to teach you, but I can't like everyone. And it's the same with the people I've invented.
Some characters, I almost love to hate them. They are mean and horrible and I admire them despite myself. Some I find petty and conventional, and I struggle with the contempt I feel, and the difficulty of delving within them to find a nugget of gold. It’s there. You can find something in common with anyone if you try.
But there’s one thing I don’t find hard at all, and that’s being mean to the characters I love.
After I’ve gone round maiming and widowing like a literary pre-menstrual goddess Kali before she’s had her breakfast, I ask myself this. My characters are decent people. Why am I treating them like this? Can I be locked up? Should I be locked up?
But a story without pain and suffering will not advance. Your characters needs to be dragged out of their complacency, forced to take action, called to the Hero's Journey, or at least to that uncomfortable breakfast meeting where they can regulate their blood sugar.
This is all the advice I can give you: Don't hold back. Don't cause unnecessary pain as a plot device, of course. Any pain you inflict must be necessary for the plot. (Everything that happens must say something about the plot, and I mean Every. Little. Thing.) But - don't be coy. I know you love this person deeply, I know you know them and you have sat quietly before you write, thinking your way into their physicality and their head. But allow them to be hurt. Let them bleed. The bloodletting will make your story happen.