YOU should yap about NICO and anger!! what does anger look and feel like for him? what sets him off? how does his anger change and shift over the years? how does he cope with anger?
Anger seizes Nico around his neck, gripping tighter and tighter (like a noose), traveling up from his chest to the back of his head. His chest, where it should be inflamed--and indeed it sometimes is--often rests cold and still, a hard knot in the place where his heart should be. Emotions otherwise bound up tight to prevent the rest from leaking out, only allowing the anger to escape. And as that anger travels up his neck, it sets fire to the back of his mind, clouding his thoughts with smoke so only the anger remains, giving him new energy that he wouldn't otherwise have. Sometimes the only energy and drive he has.
His teeth grit together, lips pulled back in a feral snarl, a dark light dances in his eyes. A dare, a promise, for what might to come if his anger is further tested. Shoulders are stiff, bound up in the same tension as his neck, but more ready to spring, more ready to fight. When Nico is at the peak of his anger, it's all he can do to restrain himself.
( When his anger is calmer, the cold knot in his chest still ensures its presence, but it sharpens his words instead of his blade. A cold, sardonic cut to everything he says, tempered marginally by time and patience. )
Nico's anger stems from the source of feeling wronged, of an injustice being carried out either to himself or to those he cares about. He feels broken promises deeply, again either given explicitly by someone he (previously) trusted, or implied by how a system is supposed to function. And his anger is only further fueled by harm coming from said broken promises. Nico's anger carries a holy element, a winnowing away of what is wrong in the world out of the desire to make it a better place to live. But a pride also lurks as an additional fuel for the fire-- he believes in his version of justice, his version of right and wrong, making it harder to see other perspectives on a situation.
But his anger tempers slowly over time, becoming less volatile as he himself begins to heal. The places where he's broken continue to mend and the cold, stillness in his chest begins to crack. He allows himself to feel more emotions, to be worthy of those emotions, and thus the anger has less grounds to present itself. It does sometimes flare hot, but not as hot as before, and it is usually more targeted.
Nico still feels a lot of his anger his justified, and he still needs to work on holding grudges, but he has gotten better at seeing more perspectives, understanding others from where they're coming from. Because of this, his anger doesn't come up as much, and when it does, it doesn't quite consume him anymore.