Revision: relative clauses with relative pronouns in the nominative and the accusative
Relative clauses are subordinate clauses. As a rule, they cannot stand alone and are dependent on a superordinate main clause or subordinate clause. Relative clauses give more detail about a noun or pronoun in the superordinate clause. A relative clause generally comes directly after the word to which it refers and a comma. The conjugated verb is normally at the end of the relative clause. The relative clause is linked to the superordinate clause with a relative pronoun. This relative pronoun refers to the main word in the superordinate clause.
Nico besucht Pepe. Er (= Pepe) wohnt in einem Hotel.
Pepe is the main word.
Nico besucht Pepe, der in einem Hotel wohnt.
The main word determines the Genus (grammatical gender) and Numerus (singular/plural) of the relative pronoun that connects the relative clause to the superordinate clause. As Pepe is a man, this is masculine singular.
The Kasus (case) of the relative pronoun depends on the grammatical function of the relative pronoun in the relative clause. In the first sentence (Nico besucht Pepe), Pepe is the accusative object. But in the second sentence (Er wohnt in einem Hotel), Pepe is the subject, and so is nominative.
The relative pronoun is masculine singular and is in the nominative: der.
Take a look at an example with the accusative:
Nico spricht mit Pepe. Er bittet ihn (= Pepe) um Hilfe.
In the second clause, Pepe is the accusative object. The relative pronoun thus is: den.
Nico spricht mit Pepe, den er um Hilfe bittet.
Grammatical terms in German:
der Relativsatz: A relative clause is a subordinate clause that gives more information about a noun or pronoun in the superordinate clause.das Relativpronomen: A relative pronoun links the relative clause and the superordinate clause.