Li Yang is a beta. He is a person with a very plain personality who came from the normal world.
He has witnessed the development of many common ABO plots, such as O pretending to be B but ends up overturning, AA's forbidden love, OO fighting against worldly views and being together, AB lovers getting together and then A meets a 100% compatible O, weak A and strong O, delayed gender awakening, gender reversal and other bloody plots.
In these experiences, he slowly grew up and understood the meaning of existence as a B and the rules of survival for betas. He slowly accepted this fucked up world and found the love of his life.
Purpose: personal exploration of the world, continuous exploration and practice of self-worth, and final self-growth.