Who is The Younger Brother (Paulo) from The Lover and what is their importance?

The younger brother is about one year older than the narrator. Aside from one instance, the younger brother is unnamed. He is largely unexceptional and appears non-intellectual, insipid, and dull. He is, however, depicted as a respectable child though devoid of ambition. The younger brother becomes the receptacle of all the family's failures and the particular object of hatred from the older brother. He is dominated by physical force and beaten on numerous occasions by the older brother, and on at least one occasion by the mother. Even after the older brother is sent to France, the younger brother appears mechanical and without spirit.

When the family leaves French Indochina, the younger brother enjoys a period of emergence aboard the ocean liner. He wins the affections of a fellow passenger—a married woman—and indulges in an affair with her in front of her husband. Fortunately, the woman's husband is detached and uncaring. Their affair ends when the ocean liner reaches France.