A soft-spoken and surprisingly welcoming man, especially towards the Sole Survivor, an American. The guilt over nuking the Commonwealth using the missiles on board his submarine changed him. He had been isolated after his Yangtze-31 struck a mine not long after the Great War, the radiation from the damaged reactor turning the captain and his crew into ghouls.
For two centuries, he eked out an existence scavenging what he could from the destroyed city and fighting off raiders, gathering intelligence and information that would, one day, help him repair the vessel and return it to Zhongguo, his home. There, he will rebuild or die. Whatever his fate, he wants to see his home one last time. Trouble is, the Forged and other raider gangs might be a little too much to tackle for the ancient ghoul - submariner or not. His only companions during these two centuries were his crewmates. Unlike their captain, they have succumbed to radiation poisoning and turned feral. Zao couldn't bring himself to put them out of their misery.
Zao recalls firing his ship's nuclear salvo as ordered, and it is clear that he is responsible for the nuclear detonations specifically in the Commonwealth. He reflects on his actions with guilt, regretting the destruction he caused. It is possible that one of the nuclear warheads fired from his submarine was the one that created the Glowing Sea. He claims that the city was already ruined when he arrived at the port.
He seems to consider the Liberation of Anchorage "a joke." He is clearly aware the war is over, but he still holds traditional values of the Old World. He refers to the Sole Survivor as "capitalist" and "American," especially if they attempt to negotiate a higher reward for providing assistance.
Should the Sole Survivor call Zao "commie," they will demand that they die for destroying their country and immediately turn hostile.
Should one help him repair the Yangtze reactor, he provides three homing beacons for small tactical nukes fired from the Yangtze as a reward, remarking that "[he does] not want to bring the fire home." Zao will also give the player character his sword, a unique weapon, if all three Charisma checks are passed.
Zao is the first human character from pre-War China with whom it is possible to converse in the Fallout series.
'Zao' may be a misspelling of the common Chinese surname 'Zhao'（趙）, since the surname 'Zao' indeed exists, but is very uncommon in China. According to zupulu.com, his surname may be 造, 棗, 皂, 隞, 遭, 灶 or 早 in Chinese.
'Zao' may also be referring to the Chinese character for "rotten" or "horrible"（糟）since he is now a ghoul.
He often mixes Chinese with English in his speech. Despite the Chinese words being fairly decently pronounced, albeit not with a very clear, typical northern Chinese accent, Zao's lines in Mandarin include some fairly awkward grammar and syntax, especially in the way he mixes Chinese and English, which is entirely arbitrary and unlike how real-life Chinese-English bilingual people mix them. Words used include:
Yangtze = 揚子
He ping = 和平, Peace.
Jiang Shi = 殭屍, Zombie/Ghoul.
Qian ting = 潛艇, Submarine.
Wei xian =危險 Danger.
Gu shi = 故事, Story.
Bao Wu = 寶物, Treasure.
Shi de = 是的, Yes.
Tong ku = 痛苦, Pain and suffering.
Xing yun = 幸運, Luck/Fortune.
Bu xing = 不幸, Misfortune.
Xie xie = 謝謝, Thanks.
Zhongguo = 中國, China.
Jia = 家, Home.
Zu guo = 祖國, Motherland.
Xian jin = 現金, Cash.
Yi han = 遺憾, Regret.
Jian = 劍, Sword.
Gong zuo = 工作, Work.
You xiu = 優秀, Excellent/Outstanding.
Bei = 悲, Sadness (however, Bei is usually associated with other adjectives instead of on its own, for example, Bei Ai - 悲哀', lit. sorrowful)
Jia ren = 家人, Family member.
Jue wang = 絕望, Despair.
Zha dan = 炸彈, Bomb.
Xiao xin = 小心, Be careful.
Si wang = 死亡, Death.
Bao zha = 爆炸, Explosion.
Zhu, zi ben jia, qu si ba! = 豬，資本家，去死吧, Pig, capitalist, go to hell!
↑The Sole Survivor: "Where are you going to get that?" Zao: "Ah... Now that is the right question to ask.200 years ago, I launched all of Yangtze's high-yield nuclear missiles. As ordered. For 200 years, I have lived with that guilt. That shame. So much fire Such bei.But one missile failed to launch. You must go down. Remove the warhead. Then bring it to me." (Zao's dialogue)
↑The Sole Survivor: "Have you been here for 200 years?" Zao: "Wa! It has been that long? Shi de. Yes. I suppose it has.Long ago. Just after the fire. Yangtze struck a mine. My qianting barely made it here into harbor.City already ruins by then. Few noticed us. Fewer cared. Too much tong ku.Your arrival is good xingyun for me. I need help, you see.Yangtze is not... ahh... Seaworthy. You will help me fix her?" (Zao's dialogue)
↑The Sole Survivor: "Have you been here for 200 years?" Zao: "Fushe! You say... radiation. From damaged reactor. Turn me into this guai wu.My crew... gone. I cannot think on their fate."
↑The Sole Survivor: "Who are you?" Zao: "Zao! Captain of the Chinese Navy! I sail the Yangtze-31. This qianting. Submarine. My beautiful boat.Speak harsh words of me if you must. But my Yangtze... Speak of her with respect.Why are you here? War is over. Long over. And my Yangtze holds no bao wu. No... treasure. Nothing for you to plunder." (Zao's dialogue)
↑The Sole Survivor: "Why would you trust me, a stranger?" Zao: "Trust is risk. But a man must plow with oxen he has.You are not like raiders that board my quianting. My Yangtze. You show peace. Xie xie." (Zao's dialogue)
↑The Sole Survivor: "What will you do with the submarine once it's fixed?" Zao: "Ah. I sail for Zhongguo. Return to China. Where I belong. My jia. My home?" (Zao's dialogue)
↑The Sole Survivor: "You can go to Hell. You're part of the enemy that destroyed my country." Zao: "That is... sad. Um... unfortunate. Bu xing. I hoped that after 200 years, we could forget past hatred. I shall wait for someone more willing to help me." (Zao's dialogue)
↑The Sole Survivor: "Why don't you get it?" Zao: "Ah... Because I have different task. While you are getting warhead? I will prepare the reactor. But now I must... warn you. There is danger. Wei xian! Old crew... still down there. Not okay like their captain. Worse. They do not harm me. But they will kill you! I... I cannot kill them. Still, they are my crew. My family. Jia ren, all of us. But you must do what you must do." (Zao's dialogue)
↑The Sole Survivor: "What will you do there?" Zao: "Anything Zao can do. If China is gone, I will build. House by house.And if no houses can be built, I will die. My jia. At peace." (Zao's dialogue)
↑The Sole Survivor: "Nah. No sweat. The radiation did give me super powers, though. X-Ray vision. Love the leopard g-string." Zao: "200 years, and your humor is still bad. America liberating Anchorage? Now that was a good joke.Now. Here is what you must do. Head down to the reactor. Take dampening coil and warhead with you.First, insert the dampening coil. Carefully. Xiao xin.Then, put warhead into the reactor. As you do that, I monitor power levels from the control room.Do not put in warhead first! Do that? Si wang. Death, for you and me both." (Zao's dialogue)