Rama led his army of monkeys and bears south to the ocean. There they camped on the shore, deciding how to rescue Sita from Lanka.
To their surprise, a rakshasa came flying through the sky. "Rama," cried the rakshasa, "give me refuge!" It was Vibhishana, Ravana's righteous brother.
"He can't be trusted," shouted Sugriva. "I'm certain he plans to kill us in our sleep." Angada and Jambavan agreed that Rama should send Vibhishana away.
But Hanuman said, "I know this rakshasa; I saw him speak in Sita's defense, defying his brother. We can trust him."
So Rama gave Vibhishana refuge.
Inspired by: Valmiki's Ramayana.
Notes: This is the Yuddha Kanda (Book 6), sarga 5 and following. Vibhishana defects to Rama's side in sarga 17.