Jillian was born the daughter of Gumar the Black, one of the most powerful trolls in all of Trolltown. Growing up, she had been taught to be loyal and devoted to her father's cause, which was to protect their people from human encroachment on their lands. She had grown into a fierce warrior, and by the time she was fifteen years old, she had fought in countless battles alongside her father.
One day, Jillian and her father were called upon to fight against an army led by Jim Lake Jr., the Trollhunter. They knew it would be a difficult battle, but they were prepared for whatever came their way. However, no matter how hard they fought, it seemed that Jim Lake Jr. was always one step ahead of them. In the end, Gumar the Black fell in battle and was killed by Jim Lake Jr.
Jillian stood there in shock as she watched her father fall. Tears began streaming down her face as she realized that he had been right all along; that humans posed a real threat to trollkind and needed to be stopped. But instead of fighting back against Jim Lake Jr., Jillian chose to betray her father's memory and join forces with him.
Jim Lake Jr. welcomed Jillian into his ranks with open arms and promised her a place among his warriors if she proved herself worthy. She agreed, determined to prove that she could be just as deadly an opponent as any other troll hunter.
Little did Jillian know that this decision would come at a terrible price: that one day, she would have to turn against the very person who had saved her life and become an enemy of everything she held dear.