This is BOX! She's a cannibal.
Anywho, BOX is the "result" of an experiment performed by the Angringer Foundation (more detail later) concerning how long a person can endure until they resort to cannibalism to survive.
Her design is based somewhat off of the Wendigo, a creature said to have once been human, but became a starved monster after resorting to cannibalism. She escaped from the Angringer Foundation after the first rebellion from D-L3 (a previous picture), and had since then lived in the woods, preying on wandering humans to survive, as the trauma she experienced forced her into believing only human flesh could keep her going.
Originally, BOX was a twelve-year-old girl with self-image problems, and resorted to starving herself in order to make herself more "attractive". She ran away from home after her parents became concerned for her health, and she believed they did not understand. After finding her lost in the woods, agents of the Angringer Foundation abducted her and thus, said experiments were performed. Even after the trauma, a part of her still remained, the part of her that thought she was still ugly somehow. This is where the box comes in. The box and branches, in her mind, serves as a way to disguise this "ugliness" that she no longer knows why is there.
She meets Jeremy out in the forest with D-L3 and at first, tries to eat him. After D-L3 leads Jeremy back home through the window, BOX could no longer follow, out of the instinctual fear of being trapped again. After the second encounter, Jeremy confronts her, attempting to make peace with whatever he had to his disposal, in this case, maple syrup.
Yes. Maple syrup. Ironically, this was the only other thing that BOX would tolerate eating, and through this, Jeremy becomes friends with her.
Similarly to D-L3, she is primarily silent, but uses the occasional rumble to communicate. She has also used a radio as communication by signalling to other stations at precise times to form a coherent sentence.
Let me know if you guys have any confusion over BOX as a character or her story! I'd be happy to answer them!