Can we talk about this scene? Because both of their reactions are complex and morally gray. Miss Quill wants revenge because she sees it as the only way to possible get some closure. Life is about fighting back. Miss Quill needs to fight back against those who have harmed her and her people, because if she doesn’t fight, then she isn’t living. She’s single-minded in this. Miss Quill puts the destruction of the Shadow Kin above a chance for her own freedom and even her own life.
Then there is Charlie, who clings to his Rhodian morals and sense of justice. He doesn’t have the same thirst for revenge as her, but he believes in punishment–harsh punishment– for those who kill. He hesitates–not because he opposes genocide, but because he clings to hope. Yes, Charlie has more qualms about it than Miss Quill (many of which are prompted by Matteusz), but if he wanted to, Charlie could easily justify genocide as a righteous punishment for what the Shadow Kin did. The reason he doesn’t want to–the real reason–is that Charlie doesn’t want lose the Rhodian souls and the hope they give him. That is what dictates his actions.