User blog comment:Kaido King of the Beasts/Talk about the Bloodbath-I mean Chapter 767!/@comment-220.255.1.37-20141116104315/@comment-24287735-20141116123335

Vergo was somewhat acquainted or friends with Doflamingo since at around age 10. This is why he was assigned as the first Corazon before Doffy's brother Rocinante took the position much later.