Werewolves have been around for as long as humans, they are made whenever a werewolf bites a human while in non human form, the bite must pierce the skin. Not all bites are infectious, usually the more severe the bite the more likely it will infect if the victim survives. Werewolves who wish to make another usually will bite the same place repeatedly. Cauterizing wounds soon after being bitten usually prevents infection. Werewolves can transform at will into very large wolf shapes, larger than a man and twice the size of a natural wolf. Werewolves are much stronger than humans, they also regenerate quickly from wounds and have heightened senses of smell. They are at home in nature, enjoying the smell and feel of the natural world, by contrast highly artificial smells and environments make them uncomfortable, such as smog or cigarette smoke.
Werewolves and the moon
Werewolves transformations aren't entirely linked to the moon, they can change at any time. However they are much weaker during the new moon. Also during the full moon werewolves are subject to a condition known as Lunacy. Lunacy is a kind of rage or insanity that sets upon werewolves during the full moon, it makes them anger extremely quickly and be very prone to violence, some even hallucinate during it. It's very common for werewolves to transform during this time and rampage, and a full nine tenths of new werewolves are bitten on the full moon from werewolves under the influence of Lunacy. Werewolves who can resist changing for 2-4 months are able to partially resist lunacy and are much less likely to end up killing people during it.
The change takes about a month and begins gradually, the new wolf's senses first begin to develop, then strength and healing abilities. The ability to transform tends to come quite late in the month, and many don't realize they can transform until their first full moon.
Werewolves and silver
Silver causes itchiness and rashes to werewolves that wear it for prolonged periods, additionally silvered weapons are liable to cause temporary in werewolves struck by them.
Werewolves and magic
Werewolves are close to nature and have an intrinsic sense of what is an is not natural, as well as a dislike for unnatural things. While technically werewolves could perform magic it causes a strong unpleasant feeling whenever it's performed, most believe that this feeling is nature crying out against it and are strong proponents of it stopping being used.
Werewolves and vampires
Werewolves are the embodiment of natural world, vampires of the unnatural and there has always existed a degree of antipathy between them. Vampires and werewolves find each other's presence unpleasant, this doesn't preclude some from becoming friends or getting along, it is akin to a person having bad BO. Unpleasant to be around, but not debilitating. Again many Werewolves believe this is nature telling them that the vampires should be destroyed.
Werewolves and death
Upon dying a werewolf will turn back into their human form, this isn't instant however and normally takes about an hour.
Werewolves can get pregnant just like normal humans, there is a chance the child will be born a werewolf. Having a werewolf mother gives about a fifty percent chance for the child to be a werewolf, a werewolf father about a ten percent chance. Werewolves can transform and are subject to lunacy at any age, even as infants, although changing is usually beyond their control until around the age of ten. Because of this even werewolves who want wolf children usually prefer to have a human child and turn them once they're old enough. Children born werewolves almost invariably have to be hidden from the world until they reach an age where they can control themselves.
The skin of a transformed werewolf is a prized possession, garments made from werewolf furs or tanned werewolf leather are extremely tough, wind resistant, yet light and supple. Most werewolves can smell when a piece of clothing is made from their skin and it's normal for those who wear it to be targeted for vengeance by the pack. Because of the werewolf's transformation upon death, the hide must be harvested very quickly or even in some cases, while they are still alive.
Werewolves are mostly mentally unchanged from the humans they were before, except that they tend to have a tendency towards anger, violence and group socializing. These tendencies aren't so profound as to change their underlying nature however. Some werewolves go primal, embracing the Lunacy. Most try to control themselves during that time, or lock themselves up. Werewolves psychology tends to shift towards very naturalist world views, they tend to oppose industrialization and many have been linked to eco terrorist groups.
Werewolves are generally considered the most powerful soldiers amongst the supernaturally gifted, a combination of that and how easily they can create more if the need presents itself leads to them being the most sought out mercenaries in the supernatural world.