Warning: The following text contains spoilers relating to the plot of Eye of the North.
Both Jora and Svanir were possessed by an unknown Ancient Force while hunting wolves at Drakkar Lake. Jora fought off the possession and lost the ability to assume the form of the bear, while her brother became possessed and mutated into the Savage Nornbear. The Savage Nornbear has plagued the Norn populace, raiding farms and killing all that cross its path ever since. That Ancient Force is highly suspected to be the Drakkar, the Ancient Dragon beneath Drakkar Lake.