Ravana went looking for Vali, the monkey-king, wanting to fight him. He found Vali on the ocean's shore, engaged in worship.
He planned to sneak up on Vali from behind, but Vali grabbed Ravana and shouted, "Got you!" He then tucked Ravana under his arm and soared up into the sky.
Down below, the rakshasas saw their king struggling to get free. They chased Vali but could not catch him.
After flying around the world, Vali landed and let Ravana go.
"I want to be your friend, great monkey!" said Ravana.
Vali laughed and agreed; thus Vali became Ravana's ally.
Inspired by: The Ramayana (Uttara Kanda, 34).
Notes: Vali's wife Tara plays a role in the full version of the story because Ravana first goes to Kishkinda; Vali is not there, but Tara speaks with him and warns him that Vali is sure to defeat him.