When Lord Siva appears to Ravana to grant his wish, Lord Vishnu manipulates Ravana's mind and makes him wish for Goddess Parvathi. As Ravana proceeds home with Goddess Parvathi, Narada meets him midway and tells him that his companion is a fake Parvathi.
When Lord Siva manifests before Ravana to grant his wish, Lord Vishnu subtly influences Ravana's thoughts, leading him to long for Goddess Parvathi. As Ravana travels home with the supposed goddess, Narada intervenes and discloses that his companion is actually a false Parvathi.