I agree with this post, and I want to add sth, I hope that's okay, OP.
Rosinante's anger - when he showed it - idk why but it didn't scare me. It didn't scare me like Doflamingo's anger. Doflamingo's anger fckn terrifies me.
I think you may have cracked why. Because Rosinante's anger came from a kind place. It was also presented differently. It was presented in a bit of a light-hearted, joke-like way. Even though he is burning down a hospital.
Also, even in anger, once they start their journey, Rosinante never hurts Law. He carries him around, yeah, but he never raises a hand against Law again. Rosinante isn't going to hurt his loved ones in anger. Doflamingo shows he will. I think this is also a factor of why Doflamingo's anger is terrifying and Rosinante's isn't as terrifying.
I think being Corazón helped Rosinante get that anger out. I think being Corazón probably made Rosinante realise how angry he is. But having an outlet in form of killing pirates... I think that was pretty good outlet for him. He gets to be grumpy, he gets to be angry, he gets to kill. (This is not to say Rosinante enjoys killing people.)
Also, I want to mention the Bottle Smash™ both DQ brothers do it.
But it also feels different, even though I think the source of the smash is their distress/anger.
It feels different. Is it because of what or who they're doing it? Rosinante does it because he's helpless to help Law. Doflamingo does it because the wine isn't helping him therefore he smashes it to smitherens.
Yeah, Rosinante is angry. Rosinante also didn't pull the trigger. Even if he was angry at his brother. Because his anger comes from a different place, I think.
But Doflamingo did. Doflamingo pulled the trigger very very full of emotions, and it's shown he expresses experiencing a complex flood of emotions in him by either anger or laughing. He is vulnerable, so he acts out with anger.
Rosinante doesn't have this problem with his emotions, I think. Yes, he acts out in anger, but he never lets it fog him to the point he hurts someone he loves.
Doflamingo, unfortunately, does not have that same sense. (I'm not saying he killed Rosinante in a fit of anger, he did not. He was 100% aware and there mentally, he was aware of his actions very much.)
Doflamingo's anger was always embaraced and encouraged, so he continues using it to express his emotions. North Blue Doflamingo was fckn terrifying bcs of how QUIET he was, at least to me. He didn't laugh as much as he does later. He didn't taunt people as much and got under their skin. Him expressing & processing his emotions in a safe way was never taught to him. He also was never encouraged to say what he feels. He was in a very masculine, tough guy surrounding.
Anyway, thank you for making me understand a bit more about Rosinante, OP, which also consequently helped me figure out a bit more about Doflamingo too.