Look again at this
sentence:
The man
who lives next to me has a goat.
In its own clause, who
functions as the subject. who is the subject
of the verb lives. For this reason, who
is in the nominative case. But the relative pronoun
does not always function as the subject. Consider the
following sentence:
He is the man whom
you saw.
In this example, whom is not
the subject in its own clause. you is the
subject of the verb saw. whom is the
direct object. For this reason, the objective case, whom,
is used rather than the nominative case, who.
So also in Greek, as a rule, the
case of the relative pronoun is determined by its
function in its own clause. Consider two of the
examples we have already cited:
Τιμόθεον,
ὅς ἐστίν μου τέκνον (1
Co. 4:17)
Timothy,
who is my child
The relative pronoun ὅς is
nominative because it functions as the subject in its
own clause. It is the subject of the verb
ἐστίν. The fact that it does not agree
in case with its antecedent is inconsequential.
ἐκλεκτῇ κυρίᾳ καὶ τοῖς τέκνοις αὐτῆς, οὓς
ἐγὼ ἀγαπῶ (2 Jn. 1)
to [the]
elect lady and to the children of her, whom I love
In this example, the relative pronoun
οὕς is accusative because in its own clause it functions
as the direct object of the verb ἀγαπῶ - I love whom.