Why is Gu Mang good to Meng Jinyang?

Why did Gu Mang treat Meng Jinyang well? Gu Mang never thought about studying criminal law for Meng Jinyang and studying medicine for Gu Si. Other identities are all about making money. Give them the last one. It's different now. Liu Chengzhou stood taller than her and carried heavier than her, which gave Gu Mang a new life.