For as long as there have been vampires, werewolves have been part of the vampire lore in some fashion. Several dark fantasy and vampire fiction tropes include the turbulent relationship that vampires and werewolves have. On the one hand, they share many similarities such as unnatural forms, abilities, strengths and weaknesses. However, they are often portrayed as arch enemies and are quite opposite in that werewolves are everything forceful in the natural, living realm while vampires are often portrayed as the reanimated dead doomed to wander the earth alone.
Werewolves are large, brute animals with shapeshifting abilities that rival that of any self-respecting vampire. They are also rumored to be overly emotional, given to outbursts of anger and fits, and unable to control themselves once exposed to that wondrous magical orb, the full moon. The original werewolf lore can be traced back to a time when Christians associated Pagan rites of passage into the warrior class as true transformation into the devil or a kind of channeling of him. Basically, a misunderstanding of the Pagan belief systems and judgment based on little to no factual information led to werewolf trials that rivaled the witch trials of Salem. (Mass hysteria was rampant in medieval Europe.) There are claims that the werewolf myth was also used as a way to explain the behavior of serial killers in medieval France.
The moon, for the vampire, is a source of healing and strength. I suppose it could be construed as such for the werewolf as well as a weakness, causing supernatural metamorphosis although at inconvenient times. Perhaps both the vampire and werewolf are slave to the moon and her whims.
In some vampire lore, the werewolf and the vampire are literally the same creature, though referred to by different names with slightly different attributes. The vampire was thought to be able to transform, like Dracula, into a werewolf or bat or mist. It was simply a variation on the original vampire lore.
In other stories, the vampire and werewolf are mortal enemies, though they are like minded in their hatred of mankind. Their very natures are polar opposite with the vampire being portrayed as wealthy and intelligent, a socialite of sorts at times, and the lowly werewolf being a simple-minded brute at the mercy of his animalistic nature. It’s no wonder then that the relationships between these two recurring characters in fiction is a complex one.
I personally find the possibilities that this juxtaposition of character traits brings very alluring. Maybe we’ll see the animal side of the vampire, the aristocratic side of the werewolf, the fangs, the moon, the passion! It can be combined in so many interesting ways to create conflict that is still drawing us in.
Alas, every good villain, or love interest depending who you ask, is doomed to have his weaknesses. Werewolves are no different, but silver certainly seems to be the only one.
The werewolf legend continues to evolve, often alongside the vampire. Sometimes friend to the vampire, sometimes foe, the werewolf is not hindered by the sun and it would be difficult to say who would ultimately come out on top of this centuries old pairing.