Vilkas

 is a Nord lycanthropic warrior and resident of Whiterun. He is a member of The Companions and The Circle, the secret order within The Companions. He serves as the Dragonborn's shield-brother in several of the Companions' quests. As with all Companions, he is usually found within Jorrvaskr, located in the Wind District of Whiterun.

After the Companion's questline is completed, Vilkas will eventually give the quest Purity. In this quest, he will ask the Dragonborn to cure him of beast blood. He is available as a follower and also eligible for marriage after completion of The Companions questline. Vilkas can also be selected to act as Steward for the Dragonborn if is installed.

Quests

 * Take Up Arms: Prove that you're worthy to join the Companions.
 * Purity of Revenge: Retrieve the Fragments of Wuuthrad and wipe out the Silver Hand.
 * Glory of the Dead: Cure Kodlak Whitemane's spirit and prove to be a true Companion.
 * Purity: Help a member of The Circle give up their beast blood.
 * Escaped Criminal: Track down and kill an escaped prisoner.
 * Rescue Mission: Rescue a kidnapped citizen and escort them to their home.
 * Dragon Seekers: Defeat a dragon with Vilkas or Farkas.

Background
Vilkas and his brother Farkas, were both raised in the Companions' Hall. Their father, Jergen, left them there while he went to fight in the Great War and never returned. Eventually, Vilkas and Farkas both officially joined the Companions. They were said to be the youngest members to ever join, though this may be a play on words by Vignar Gray-Mane, referring to the twin's young age during their residence at the Companion's Hall rather than the age at which their membership became official.

Personality
At first, Vilkas seems to think the Dragonborn isn't worthy of being a Companion, but he eventually warms up to the idea after the completion of Glory of the Dead. Vilkas is well-spoken and considered to be an intelligent man by the other Companions, the counterpart to his brother's physical prowess. Vilkas, along with his brother Farkas and Kodlak, resists the call of the beast-blood, choosing instead to refrain from transformations. However, he struggles with the side-effects more harshly than the others.

Vilkas is also thought of as a hot-tempered man. For example, during Purity of Revenge, he does not hesitate to avenge Kodlak's death. However, he does later show remorse for his rash actions, as seen in Glory of the Dead, during which he refuses to complete his journey to Ysgramor's Tomb, feeling himself unworthy.

Notable loot

 * Wolf Armor (Exception of helmet)
 * Gold.
 * Anything given as a follower.
 * Steel Sword

Trivia

 * "Vilkas" means wolf in Lithuanian. His brother's name, Farkas, also means wolf, in Hungarian.
 * If Vilkas is a follower, the Two-Handed skill can be trained in for free. Buy training, then check his inventory and take the money back.
 * Vilkas usually says that he likes and prefers two-handed weapons, and he always uses them when he is the Dragonborn's follower or when he is in a quest. However, Vilkas used a one-handed sword and a shield when training against the Dragonborn in the quest, Take Up Arms.
 * Vilkas may be randomly encountered out in the wilderness killing a giant along with Ria or other Companions.
 * If Vilkas is a follower, he will leave if the Dragonborn assaults or murders an innocent civilian, just like his brother, Farkas.
 * He has claimed to have killed every type of creature in Skyrim and thinks a trip to Morrowind is in order.
 * If the Dragonborn has 2 manors, provided the Hearthfire DLC has been downloaded, and Vilkas is appointed as steward, he may head to the other manor at night and sleep there instead.
 * If Vilkas is appointed as steward, he may return back to Jorrvaskr.
 * Therefore if you want improvements, or you want to buy materials, you have to travel to Whiterun.
 * If the player turns into a werewolf while they have Vilkas as a follower, Vilkas will attack the player, despite the fact that he himself is a werewolf too.

Bugs

 * When asking Vilkas for some extra work, he may ask that a kidnapped citizen from the Reach be rescued. If this citizen is Eltrys and he has already died in the quest The Forsworn Conspiracy, one may just find his body in the cave. This will not allow the Dragonborn to continue the Companions questline.
 * This can be fixed by asking him to become a follower, so long as the Dragonborn has one already. He will say that he cannot, and then go back to his normal routine, or by going to the city where the bounty is and paying it.
 * Another option is sneaking and invisibility; with a high enough sneak skill and/or potions/enchanted items one can remain beneath his detection threshold thereby avoiding triggering his conversation script.
 * One more option for the above is to attack him until he is in submission, go to jail, then return.
 * One possible way to get out of this bug is to keep doing Farkas' radiant quests after he is cured of Lycanthropy. Make sure to do the quest where Farkas wants to kill a dragon. Vilkas' Purity quest appeared after completing Farkas' dragon quest.
 * If encountered as part of a random encounter, he may remain at the scene of the battle and never return to Jorrvaskr.
 * After being cured of his lycanthrope, Vilkas may unequip every piece of armor he has on and runs back to Whiterun in his underwear.
 * After starting Purity, Vilkas will tell the Dragonborn to meet him at Ysgramor's Tomb, making any current companion leave. Vilkas will then remain in Whiterun and ignore the quest he gave, resulting in the Dragonborn being unable to have a companion.
 * Use the console command  to end the quest.
 * After completing the Companion's quest line, upon reentering Jorrvaskr, Vilkas will keep running up to the Dragonborn and talking to them.
 * This may also occur when the Dragonborn kills two innocents, after which Vilkas becomes aggressive. If you use a harmony spell of some kind to calm him, he will keep running up to the Dragonborn and keep talking, even in the middle of a battle. Reloading a previous file can fix this.
 * Vilkas may randomly stop talking but will go back to normal.
 * When Vilkas is a follower in Purity Of Revenge, if the Dragonborn sneaks, he may be stuck in sneaking.
 * Possible solution: Transform into a Werewolf.
 * If married, rarely he may walk around in his underwear. The only fix known so far, is by activating him as a follower and taking away some kind of apparel from his inventory. That should re-activate any other clothes he is wearing.
 * Sometimes, upon seeing the player, he may walk up to them with his weapon drawn, and act like he was talked to. He will continue to do this even if he is recruited as a follower, and the only way to have him stop is to either go out of his range of sight, where he will start again if he sees the player again, or kill him.
 * Vilkas may not give the quest to cure himself of Lycanthropy.