i believe you need to be male(choose the male presest character just incase) , have good-looking trait(probably not). when ma rin asks you to look into xiwen before the Zone you agree, tak to xiwen at the volcano before talking to Tang Wei. When you wake up and talk to Ma Rin just agree to the things she want you to do, then when you learn about Xiwen tell her(might not be needed). then when you start choosing elders choose her.