Were werewolves the guardians of vampires in myth as mentioned in “Underworld”?
I am unaware of any incidence in genuine myth of werewolves serving as the ‘daylight guardians’ of vampires as in Underworld. However, some myths do indicate a connection between werewolves and vampires. I have been unable to find the reference exactly in my library, sorry, but in some cases, a werewolf was considered an intermediate stage between human and vampire, and was condemned to become the undead upon death. Or, in other words, kill a werewolf and he’ll come back as a vampire! (of course there were LOTS of other indicators of who would become a vampire upon death, not just being bitten. Apparently, anyone with red hair, or blue eyes, or lots of body hair, or a dozen other features, could become a vampire when they died.) Incidentally, in a lot of vampire myths, vampires could take the forms of animals, such as wolves. Although, it’s also true that in the VAST majority of the mythology vampires can walk around in daylight anyway.