Trey decided to become shaman king because                    

                                                                              he wanted to save the minutians. But finally he

                                                                                meets Yoh and they fight. It was a hard fight for Yoh

                                                             but he wined. After that Trey wanted to help Yoh to become the shaman king

                                                                             because he saw Yoh can become the shaman king and save

                                                                                         the world from the hands of evil like Hao.