Throughout The Vampire Diaries Series
The first mention of the Vikings in the series was made in Smells Like Teen Spirit by Rebekah Mikaelson, an Original vampire. She introduced herself as the new student in Alaric's history class and brings up the Viking settlers in the United States when the class began discussing the founders of Mystic Falls.
In Ghost World, Mason told Damon that he knew about the weapon that could kill Klaus. They went into old Lockwood Cellar and they broke through the wall. Beneath the wall was the tunnel which lead to a secret cave whose walls were covered in drawings of the village's history, along with carvings of the names of the Mikaelson family written in Runic script (an alphabet used by the Germanic people during the Viking Age).
In Ordinary People, the relationship between the Vikings and the Original Family was shown in flashbacks while Rebekah was explaining the history of her family to Elena Gilbert in order to convince her and the Mystic Falls Gang not to awaken her Viking father, the Original vampire and vampire hunter Mikael.
Throughout The Originals Series
In flashbacks to the late 10th century in Every Mother's Son, Esther Mikaelson explained to a young Klaus how starlings (and birds in general) were considered sacred to the Vikings because they helped the voyagers find land. She also told Klaus that she brought starlings with the family and the other Viking travelers when they moved to the New World from Norway.
In flashbacks to the mid-late 10th century in Wheel Inside the Wheel, a young Esther went to see her sister Dahlia to beg her for a spell that would allow her to conceive a child with her husband Mikael, as she believed she was cursed with infertility. Though Dahlia was clearly unhappy with Esther being married to a Viking and intending to have Viking children, she agreed to do the spell. However, the price she demanded for the spell was that Esther must not only promise to hand over her firstborn child to Dahlia, but every other firstborn witch child of her bloodline for as long as it shall last. Five years later, Dahlia came to claim Esther's firstborn child, a daughter named Freya, whom Dahlia brought to her home to train the child in witchcraft so Dahlia could eventually draw additional power from her. Mikael was in a battle with the other Viking warriors at the time Freya was taken, and so Esther was forced to lie and say that she had died from plague; otherwise, Dahlia promised to come back and take all of her children in punishment for breaking their deal.
In Night Has A Thousand Eyes, Mikael explained that Freya was planning to make a weapon to kill Dahlia that involved binding the ash of her oppressors (the Vikings), the sacred soil of her homeland (Norway) and the blood of the one witch who broke her heart (believed to be Freya herself) to a weapon in order to create Dahlia's sole weakness. Mikael then gave the ingredients he had procured to Davina Claire to create the weapon; however, the weapon was ultimately destroyed by Dahlia in her fight against Klaus and Mikael. Klaus then killed Mikael, a former Viking warrior, with the white oak stake in order to obtain more Viking ash to make a new weapon.
In City Beneath The Sea, Dahlia brought Klaus' spirit into her mind (while his body was daggered) to convince him to join her side. In order to show him that they are much more alike than they think, Dahlia showed him memories from her past, beginning with when her village was invaded by Viking warriors in the mid-10th century. The sisters, who were young women at this time, hid together from the Viking invaders for a time, but were eventually caught and brought out into the open. When several of the men attempted to kill Esther, Dahlia used her magic to telekinetically throw them away from her. When they realized the two young women were witches, they decided to capture them instead of killing them, and Dahlia promised to use her magic for their purposes if they promised not to inflict their abuse on Esther.
As a result, Dahlia spent every day inside one of the Vikings' hovels, where she worked nonstop on spells for her captors while Esther picked herbs and flowers for magical use. Because of her time spent outside, Esther eventually began to grow close to Mikael, one of their Viking who had invaded their village, and eventually fell in love with him. Afterward, she decided to abandon witchcraft in favor of marrying Mikael and starting a family with him. This was a decision that ultimately devastated Dahlia so severely that she grew to hate the Vikings and everything for which they stood, and turned her into the person she became in the modern age.
The Vampire Diaries
- Every Mother's Son (mentioned)
- Wheel Inside the Wheel (mentioned)
- Night Has A Thousand Eyes (mentioned)
- City Beneath The Sea (flashback)
- The Vikings have connection with some original supernatural beings (vampires, werewolves, doppelgängers and witches).
- To kill Dahlia. the combination of sacred soil from her homeland (Norway), along with the ash from her oppressors (Vikings) and the blood of the one person she loves most (Esther, though originally believed to be Freya) can be combined to create Dahlia's sole weakness and forged into a powerful weapon against her. However, it appears that this combination of ingredients only has the power to render her mortal, and cannot kill her outright—she would still need to receive a fatal wound by either physical or magical means in order to cause her to die.