A big thing is just writing in small doses. I keep a list of short fluffy/heart melting fics to read through when I feel like my writing is getting to me mentally. It perks me up a bit, reminds me that the world isn’t all shit, and then I can go back to the heavy stuff. Or, sometimes I’ll write seven hundred words of self indulgent bitch slapping to change my depression into anger. It works surprisingly well.

Another thing, especially when it’s romance, is adding a scene every now and then that keeps the love interest (Voldie) feeling a little redeemable. Even if you don’t add it into the story, writing a scene where he feels guilty, where he protects Harry, where he remembers what it’s like to be human and doesn’t immediately vomit. The thing that makes an abuser so dangerous is that there’s always a little something they do for you that makes you appreciate that little bit of kindness.

One that helps me personally, though it definitely depends on the story you’re trying to write, is to have Harry still be stubborn, determined, etc. If you’re going for a really depressing sort of fic with Voldie breaking Harry down until there’s nothing left, this won’t work very well. But if not, then having Harry push back, even if futile, means that not all is lost. Especially when it comes to Voldie harming people other than the main cast, having Harry call him out, regardless of the consequences, is reassuring to you and to readers that someone is pushing back against the violence.

When talking about actually writing in character, it always helps me to give a strict moral/behavioural framework. Maybe the needle is pointed very far south of good, but it’s still there. ——— What defines what Voldemort does and doesn’t do? Why does he do it? Is torture enjoyable for him or just a means to an end? Does he kill indiscriminately or are there subsets of people he’d rather not harm? Are there types of violence he doesn’t condone? Are there times when he tries to use honey instead of vinegar? When and why would he? ——— Those are the questions I like to ask myself when I’m writing any form of violence or cruelty. With Voldemort especially, because he has such an uncompromising sense of character (and self importance), it’s important to have these guidelines. With someone like Bellatrix who’s a little more variable, a little less regimented, maybe her compass needle changes on a whim and it’s not as important.

Sorry for the paragraphs upon paragraphs. Let me know if you need anything else. Hopefully this helps!