Comrades-in-arms trust each other utterly and share life and death together.
Tips
history
Echoes《史记·淮阴侯列传》: 臣愿披腹心,输肝胆 — Han Xin pledging to 'open his belly and offer up liver and gall' to Liu Bang. In classical Chinese, liver and gall stand for the innermost true self.
culture
In PRC political vocabulary, 肝胆相照 is paired with 荣辱与共 ('share honor and disgrace') in the slogan describing CCP relations with the eight 'democratic parties.'