The relative pronoun is used within a complex sentence to refer to some antecedent in an earlier clause. In Latin, the relative pronoun is decline, and should fit syntactically with its own clause, rather than the case of its antecedent. For instance:
- These are not the Droids you’re looking for: haec Droidēs nōn sunt quae quaesis.
The antecedent (nominative) does not align with the relative pronoun (accusative). Also, note how easily Latin shifts and embeds a relative clause:
- These are not the Droids you’re looking for: quae quaesis haec Droidēs nōn sunt.
- These are not the Droids you’re looking for: haec Droidēs quae quaesis nōn sunt.
These are both acceptable (albeit irregular/poetic) alternatives to the sentence above.
The relatives are declined as follows–
The Essential AG: 147

Pulchre! Ego autem verbum “droids” declinare praefero ut declinatione tertia.
(E.g; droides, -is)
Concurro tibi.
(Et spero ut ignoscas mihi; oblita sum tibi dicere quod valde blogum tuum amo! Thanks for sharing your insights; I look forward to reading more.)
(Et spero ut ignoscas mihi; oblita sum tibi dicere quod valde blogum tuum amo! Thanks for sharing your insights; I look forward to reading more.)