Thorn was created by the legendary Hannah Essentiae about 500 years before the events of PSitME, when she was approximately 20. She was created to help Hannah's soul survive after the death of her body. Shortly after she was created, The Man Who Rewrote History sealed her and her brother in the Sacred Lands along with her beasts, isolating them from the rest of Vale, and changed the records to show Maximilian as her creator.
During her imprisonment, Thorn was often fighting and training. She studied martial arts, swordplay, choreography, and sharpshooting. She fought many of the beasts scattered throughout the Sacred Lands, as well as her brother, Theta. During her imprisonment, she was often irritable, bossy, and stubborn. She also raised generations of Essentiae women, continuing on to Integer's mother Maria, his litter sister Nora, and nieces. She perpetrated the events behind Side Story #1, causing the beasts to attack the heroes Danaris, Axiom, Abel, and Xaitis.
After being released from the Sacred Lands, she joined the Rebels and she became a valuable ally. She quickly grew closer to the group as well as becoming friendlier. She even ended up dating, proposing to, and becoming engaged with Danaris Loajin. Her talents with fighting and magic were a valuable asset to the team.
Thorn was created as one of Vale's first native biomechanical beings by biomechanics and ghosttech pioneer Hannah Essentiae. Hanna based Thorn's body off of her own DNA, and as such Thorn has natural abilities in magic and fighting. Her mind circuit includes the Temporally Adjacent Relative Dimension Introspection Scope, which at its creation allowed her to see all of Vale's past and future events and made her a true historian. However, it was damaged during the fight with Maximillian, and thereafter only allowed her to see the future. It was damaged once more fighting along the outsiders, thus restricting her vision to two weeks ahead. Her vision of the future was entirely destroyed by the time spell and 18 year jump.
Thorn's composition consists of various rare metals and ghosttech advancements, thus rendering Thorn almost invincible to any incoming attacks. When Thorn does take any damage, her brain is wired to activate the function associated with pleasure and joy. Thorn's personality was slowly created over 500 years as she separated Hannah's soul from her own.