"Don't you ask me how sure I am?"
"Since I believe in you, I will be sure of life and death."
When we met again three years later, Gu Li still recognized her. She was still the same as she was three years ago, and her every smile and smile could easily affect Gu Li's mind. But when we see him again, he is no longer Gu San, the little assassin who followed her from birth to death, so he changes his identity over and over again to lure her into his arms.
Idea: If you want to be the protagonist, go back to your own story