Personal Relationships by Fernanda L. Ferreira, Ph.D.
As you can see, the verb ser is not only used for permanent characteristics and occupations, but also for describing relationships between people! It would be hard to try to fit all types of relationships into a category defined as “permanent.” That is why the best description for the uses of this verb is “identification.” As you say Eu sou o irmão dela (I am her brother), you are identifying yourself and describing your relationship to someone. Here are some other examples:
Carolina é amiga de Raul. (Carolina is Raul's friend.)
As duas alunas são companheiras.
(The two students are friends/partners.)
Marcos e José são sócios. (Marcos and José are business partners.)
José e João são concorrentes. (José and João are competitors.)
Helena é filha de Orlando. (Helena is Orlando's daughter.)
Eu sou filha de Iracema. (I am Iracema's daughter.)
Minha irmã e eu somos filhas de Eraldo.
(My sister and I are Eraldo's daughters.)
Note that not all personal relationships have to do with family. Many relationships are of close friendships, competitors, or even business associations. They all have to be described using this verb. To learn more about the vocabulary of “family,” check out upcoming chapters.
