[quote=@Marcus XVI]
Think of... what between the guys? 
[/quote]

a head canon is like.. Info thats established in the past of the characters. They define the relationships between characters- its kinda like a pre written connection that your character has with another.

For example a head canon could be this: Roman sees Janos as super annoying- so he threatens to skin him and turn him into a fur coat all the time.

They're like that. Its info that doesn't have to be described during the rp or even devloped there because we've already established it in the OOC.