Petra Larsen is a member of a Norse Paganist hate group based in Norway.
History
Larsen and her boyfriend Jakob Nystrom discovered an ancient manuscript detailing the hidden locations of the ancient Berserker Staff. The pair believed that finding the staff was the key to ascending to Godhood.
After locating the first piece in the Trillemarka National Park in Norway, Larsen, Nystrom and their followers started hate-fueled riots in Oslo, Norway proclaiming "We Are Gods".
Larsen, Nystrom and their followers gained possession of the second piece of the staff after taking it from Professor Elliot Randolph in Seville, Spain. Randolph was secretly the ancient Asgardian "Warrior Who Stayed" who hid the staff in the first place and he sought to find the pieces before the Paganists.
Larsen and the Paganists then travelled to Ireland to find the final piece. There they were confronted by a S.H.I.E.L.D. led by Agent Phil Coulson who were led to the location by Randolph.
The paganists were taken out in physical combat by agents Grant Ward and Melinda May, with Larsen being defeated in combat with May.
The Berserker Staff was taken into S.H.I.E.L.D. possession. [1]