Step 1: Ravan's brothers were Kumbhakarna and Vibhishana (his son was Meghnad). Step 2: Kumbhakarna stayed loyal to Ravan and fought for him; he was killed by Rama. Step 3: Vibhishana advised Ravan to return Sita and, when Ravan refused and insulted him, he joined Rama. After the war, Rama crowned him the king of Lanka. Step 4: Meghnad was Ravan's son, and Sugriva was the Vanara king and Rama's ally, not Ravan's brother. Answer: Vibhishana.