Berserkers are individuals who wear skins imbued with the spirits of animals and use them to gain enhanced battle prowess through a frenzy known as the berserkergang. They are closely associated with the Aesir god Odin, but they also have mysterious and misunderstood connections with the ancient Shifters.
The berserkers are an enigma when it comes to the relationship between men and shifters. After cursing the shifters and later gaining the wisdom of the Well of Mimameidr, Odin felt guilt over his actions and saw the error of his ways. He can imbue some minor shifter-like power to his followers, but he can only allow so much before the individual is lost to the ancient curse. Not even the wisest god of all can truly control the same ancient power as the shifters once held. Even today, there are many tales of legendary heroes carrying into battle the spirits of animals such as wolves and bears, including kings and other revered individuals, even if their story ends with them becoming a monster and nobly exiling themselves from their civilization.
The skins worn by the berserkers are blessed by Odin through an ancient ritual. The skin itself is imbued with the chosen animal spirit, which lends some of its strength to their chosen wearer (who themselves have to undergo a ritual that bonds them to their animal skin, making animal skins not interchangeable among other individuals), so long as they give in to their bloodlust and initiate the berserkergang. An animal spirit can only be instilled into the skin of that same animal, such as a wolf skin for a wolf spirit or a bear skin for a bear spirit.
Berserkergang is a maddened state that offers the berserker enhanced strength, speed, and stamina, but in return he loses himself to the animal spirit and enters an enraged, bloodthirsty frenzy. Berserkers in rage will even attack their own allies. It is said that, while under berserkergang, warriors display extreme feats of strength and endurance that no ordinary man could achieve. Raging berserkers are stronger and faster than a normal man, feel less or sometimes no pain, and are capable of enduring far more hardship. During their rage, they can even survive wounds that would be fatal to an ordinary human. However, once their frenzy has worn off, the berserker is exhausted and drained, physically and spiritually. If they attained mortal wounds, they generally die from them after their berserkergang is spent. Some berserkers have exhibited minor shapeshifting abilities while enraged, but this is uncommon. If any signs of transformation do occur, they will wear off when the berserkergang is spent and the berserker regains control. However, any signs of shapeshifting often lead to a permanent transformation and/or the bestowing of a curse.
While berserkers are still fairly common among men of the North, Odin’s blessing is only for those who have the discipline to wield it wisely. Berserkers who give in to their rage too often and too deeply become closer to the animal spirit inhabiting their blessed skins. Any berserker can forever lose their humanity if they continue to give in to their berserkergang and persist in wearing their animal skin at all times. What kind of creature the berserker becomes depends on what kind of skin they are spiritually connected to. However, all berserkers become beastfolk, save for the wolf berserkers, which will become werewolves. If this happens, their animal skins will merge with their bodies, their spirit now merged with the spirit of the animal, and they will never change back into a human form. Despite what some tales claim, there is no way to “cure” a transformed berserker. Many mighty warriors have been exiled from their homeland, whether or not their name is still spoken of with respect, due to becoming a monster.
The berserkers who wear wolf skins take up the very risky proposition of bonding with the spirit of the wolf. Wolf spirits are the most powerful animal spirits, but they are also the most difficult to control. As a result, many berserkers choose bear spirits over wolves, since giving in to the berserkergang with a wolf spirit can be a very dangerous proposition. However, a warrior imbued with a wolf spirit can perform the mightiest and most dreadful feats of all. Should a wolf warrior lose themselves to their animal spirit, which is very easy to do given its power, they will become a dreaded werewolf.
The most common type of berserker today - thanks to the sheer danger of bonding one's spirit with a wolf - is the warrior who dresses himself in the skin of a bear. If a berserker bonded with the spirit of a bear undergoes a transformation, they become bear-folk and are doomed to their beastman form for the rest of their lives, never undergoing any sort of transformation back into a man.
Other (Raven, Ram, etc.)
While wolves and bears are the most famous animal spirits for a berserker to bond with, it is not impossible for a berserker to bond with certain other animals. Raven, boar, and even ram berserkers exist, with each of them performing incredible feats of superhuman power. However, not all animal spirits can bond with a berserker: Odin will only bless his warriors with an animal spirit if they are from the land he rules, Northrim, and if he feels they are a worthy spirit to bestow upon one of his followers.