There are three prominent Hindu philosophies today: Advaita or monism, Dvaita or dualism, and Visistadvaita or qualified monism. Now the chief exponent of Dvaita was the 13th century philosopher Madhvacharya, but that wasn't all he was. He was a Vaishnava - someone who believes that the god Vishnu is supreme - but his brand of Vaishnavism was rather peculiar. Madhvacharya thought that Vayu the god of wind, whom he equated with the Mukhya Prana or chief vital breath, was a close associate of Vishnu. And he even considered himself to be an incarnation of Vayu.
My question is, has there been any scholarship as to the origins of Madhvacharya's Vayu-centric Vaishnava worldview? Did Vayu start being associated with Visnnu before the time of Madhvacharya, or was this an innovation in Vaishnavism introduced by Madhvacharya?
Now Vayu, like other elemental gods like Indra god of thunder, Agni god of fire, and Surya the sun god, was worshiped more in the Vedic period, but now they're hardly worshiped except in certain Hindu rituals. But was there a revitalization of Vayu worship during the Middle Ages? If so that might have caused Madhvacharya to incorporate Vayu into his system.
For the record, I'm a Hindu and a Vaishnava, but I'm not a follower of Madhvacharya.
EDIT: I should note that there's a Hindu scripture called the Garuda Purana which has a few chapters endorsing Madhvacharya's Vayu-centric Vaishnava worldview. But those chapters were very likely added by Madhvacharya or his followers.