害群之马 The horse that harms the herd. A person who harms the whole group. The image comes from the Zhuangzi: “How is governing the world different from herding horses? One only removes the horse that harms the others.”
一根绳上的蚂蚱 Grasshoppers tied to one string. People in the same situation, none of whom can shirk responsibility.
有福同享，有难同当 Share the blessings, share the hardships.