The Visitor real name is "William Hunter"
In one episode of the first season, the future double of Visitor takes a picture of Raph and puts it on Facebook. The picture shows it on the profile of someone called William Hunter, although it could only be a nickname used in the present.- Or William Hunter was just one of the many random person who posted the infamous Raph picture on his Facebook wall.
Jossed. His real name is confirmed to be Renard.
- The novel "The Pack" reveals that Renard is a nickname he got after joining a group of children. The Visitor's real birth name is still a mystery.
The Castafolte working for the Time Brigade is the 'real' Castafolte
By 'real' I mean the first one, created by Germain Castafolte. All Castafolte have a barcode on the left arm. The time brigade Castafolte has one in the right arm. Maybe Germain created it with the right arm barcode. And when the Castafolte began to create duplicata, he put the barcode on the left arm because he knew he has no barcode here, and so can always prove he is the real one. The third season will have the Lombardis and the Visitor acting together
Jossed. In the tird season, Dario and Sarah works for Joseph, the antagonist.- but Raul joined the Visitor.
The Visitor's hatred of jazz has to do with the reality split.
Since he says the reality split happened in the early 20th century, maybe jazz was involved in a minor way. The Queen is related to the Visitor.
As a non-Francophone I also suspect there might be an inside joke I'm missing, but they share the same strong hatred for jazz. The Protector is the Visitor's double.
He's been absent from S4 so far, and Raph once called the Protector a cyborg. In other (subtitled, at least) mentions the Protector is a robot, but maybe he's mostly synthetic, which is why no one recognised him.