"You look familiar," Vasuki said. "Who are you?"
"I am Bhima, son of Pandu, King of Hastinapura, and of Kunti, daughter of Shurasena, ruler of the Yadavas."
"Of course!" Vasuki exclaimed. "Shurasena had a naga wife. That makes us cousins! I know about Yadu also. He was once swimming in the ocean when the naga king of that time brought Yadu to his undersea palace and gave him five naga princesses to be his wives."
Then Vasuki gave Bhima a potion endowing him with the strength of a thousand elephants, and Bhima emerged from the river more powerful than before.
Inspired by: Jaya: An Illustrated Retelling of the Mahabharataby Devdutt Pattanaik.
Notes: This story is on p. 74. The leader of the river nagas is Aryaka who then takes Bhima to Vasuki, but I left Aryaka out. The story of Yadu is in the Harivamsha. Pattanaik reports that in some folk versions, Bhima marries a naga princess and they have a son.