Cayde-6 is the most lighthearted of the Vanguard and is often accused of not taking risks seriously.1 He is also notorious for his bets, which regularly get him into trouble.
Not much is known about Cayde prior to him assuming the post of Vanguard. The earliest mention of him in the City news was 126 years ago, although he claims to be older than that.2
Cayde has antagonistic relationships with many people in the Tower, especially with Eris Morn since he stole her ship in order to infiltrate the Dreadnaught.3
"It is true that finding a Hunter representative to the Vanguard has always been ... difficult. Their independent point of view is not something we can survive without, though. And so over the years we've had Hunter mentors come and go. That is, of course, what the Dare is for." - Zavala4
Before Cayde, the Hunter Vanguard position was held by Andal Brask. While the exact nature of the Vanguard Dare is unknown, it seems that the loser of the Dare has to serve as Hunter Vanguard for some amount of time.
Cayde has a unique relationship with the Fallen. He found an unlikely ally against the Hive on the Moon,5 and has (according to his own reports) asked them for advice on how to get out of being the Hunter Vanguard.6