Qi Xing Long, like all the other Shadow Dragons, was born from the negative energy from one of the wishes made on the Dragon Balls, in his case, Bulma's wish to bring back all those killed by Majin Vegeta.
When he was found by Son Goku and Pan, Qi was causing earthquakes all over a city. After the pair saved the citizens, Goku punched Qi out of the city. When they fought him, Goku and Pan found the dragon easy to fight as his attacks were easy to dodge. The fact that Qi seemed to be rather slow witted also made him not much of a challenge, Goku and Pan even managed to trick Qi into unleashing an attack under himself by standing on his head. After this, he disappeared back into his dragon ball, apparently dying. However when Pan held it, she disappeared into it into a field of blue light generated around the ball and Qi reappeared in a stronger form. He revealed that he had absorbed a mole into himself to attain his earlier form and he had now done the same with Pan.Now Qi was able to easily fight Goku, since the Saiyan could not destroy him without destroying Pan. He even refused to fight the Evil Dragon at first and it is only when Qi killed innocent people, did Goku take him on. Even though Pan told her grandfather to destroy the dragon anyway and forget about her, Goku could not bring himself to do it. Finally, the Saiyan was ready to deliver a finishing blow, but Qi quickly reminded him that he had Pan inside him, causing Goku to hesitate. The Seven-Star dragon mocked him, only for Goku to realize Pan would rather die than see more innocent people hurt. He unleashed a Kamehameha wave against Qi, but it did not destroy him, since the presence of Pan inside the dragon made him subconsciously hold back. Goku began losing energy fast and was knocked onto a roof nearby.
Qi became much more confident and even said that he was the most powerful of the Evil Dragons. He claimed that he would become the true Shen Long and even began to act like Shen Long. When Goku did not answer the dragon, Qi said he could see his granddaughter one more time and Pan appeared, jutting out of his stomach. After Pan tried to convince Goku to fight, Qi attempted to absorb her back into him, only for Goku to grab and pull her out, causing the Seven-Star dragon to change back to his true form. In this form, Qi was much weaker and could barely fight. He attempted to absorb a bird, only for Goku to finish him with a Kamehameha wave.
Powers and AbilitiesQi Xing Long is able to absorb and possess other beings, gaining their abilities and changing into large monstrous forms. However, he depends on this ability, as without a host body, he is utterly helpless. He can also fly and fire energy blasts like most of the other characters in the Dragon Ball universe. When he absorbed a mole, Qi could dig enough to cause seismic activities and when he absorbed Pan, he could perform the Kamehameha wave.