The pair first met when Tintin rescued Chang from a flooded river along the way to Hukow. The flood destroyed Chang's orphanage and his grandfather was killed in the war. Chang helped Tintin and the Sons of the Dragon stop the smuggling operations in China run by Mitsuhirato and Roberto Rastapopoulos. He is then adopted by Mr. and Mrs. Wang.
Chang later appears in Tintin in Tibet, where he is lost in the Himalayas after surviving a plane crash and is sheltered by the Yeti. Tintin, Snowy and Captain Haddock then venture to Tibet to rescue him.
After his rescue, Chang travels abroad. He writes a letter to Tintin while in London, which is received by Tintin at Marlinspike Hall just before Bianca Castafiore's arrival in The Castafiore Emerald. The character of Chang was based upon Chang Chong-Jen, a real-life friend of Hergé's.