إِخْوَانُ الْعَلَانِيَةِ and أَعْدَاءُ السَّرِيرَةِ are two possessive constructions. الْعَلَانِيَةِ refers to what is public; السَّرِيرَةِ to what is concealed. إِخْوَانُ is plural “brothers,” and أَعْدَاءُ plural “enemies.”
Placing these opposites side by side makes the inconsistency of character clear. Prepositions also matter: إِلَى expresses desire directed toward someone; مِنْ expresses fear from someone.
The lesson is not grammar alone: outward language, inward intention, and actual conduct should be consistent.