Ruby becomes a troll because of dust infused with her heart from an accident before her aura activated. Once her aura was gone, deactivating the Dust, and forcing her silver eyed warrior powers to take over protecting her, the silver eyed warrior powers forced her to transform, manipulating her physiology to give her stone skin like a troll, which improved her strength and resilience at the cost of reduced mobility and weakness to heat from the sun, easily giving her heat strokes. Since she doesn't actually need to avoid sunlight because she has Dust for a stone core instead of the heartstone that most trolls have, she continues like the skin is a result of an improved semblance, but since it still hurts her to be in the sun, she gets a medical prognosis that allows her to keep her hood up.
Prologue- — —- —— ——— ———— ———
Dust. Man was born from Dust, strong, cunning and wise. But they are not the only ones. Other such creatures are hidden from the world, freakish to men, who fight and kill to stay alive. Men drove them to find magic, using rock to obscure their existence and fade into legend. Of course, not everything is meant to last, and millennia later, men discovered energy, contained in crystal formations, which was appropriately named Dust. Using this power of Nature's wrath, men drove back the creatures of darkness, the Grimm, who were intent on destroying the men, and in time, men built kingdoms around these deposits, locking it away from the world at large and creating society. Even so, our story begins much much later, when the flow of Dust was freely opened and accessible to people even as isolated as small islands, and we start here, in the Xiao Long family home on the independent island of Patch, a few miles off the coast of the kingdom of Vale. It has a small Huntsmen training school by the name of Signal, and a large population of a variety of peoples living on it.
At the Xiao Long home, one girl was fighting for her 'life', swinging a giant blunt scythe at the neck of a stone monster who blocked with a palm most easily. "How do you expect to kill Grimm with a swing like that? Even with a blunt scythe, you should be able to pierce the stone on my palm, and you should be fast enough that I couldn't block it if I wanted to. You need to work harder, Ruby." Said the stone monster, obviously directing the girl. He was a pale yellow, with goat horns and pale white hair on his chin and above his eyes. This was Vendel, leader of the Patch Heartstone Troll colony, though few people knew they existed. Ruby, as he called her, shook her head. "I'm too small right now, I can't build the muscle to make my swings that strong or fast. My semblance doesn't work on the scythe." She said, frowning, "I'll never be able to be a huntress at this rate!" Vendel frowned back at her. "If you can't generate the force or speed that you need, then perhaps something else should generate it. Your semblance is yours, but perhaps there's a reason it hasn't yet affected your weapon. Aura is mysterious indeed. The sun rises soon, so I will be returning to Trollmarket. I bid you farewell." Ruby nodded, running upstairs to get ready for school, and grabbing a pen and paper to write down ideas for her scythe problem. 'Problem: I need my weapon to move faster and harder. Solution one: recoil? Put a gun in the scythe along the shaft to allow recoil from firing to speed the weapon. Solution two: Vendel suggested that I may be able to speed up my weapon with my semblance, though I don't know how as I haven't been able to. He implied that it may have something to do with my clothes as well. Studying required. Solution 3; stone magic may allow improved mass without adding weight, or to improve aerodynamics' she wrote down quickly, changing and preparing to go to school.
Years Later*
Ruby struggled to breathe, leaning on her customized weapon, crescent Rose, and taking deep breaths. Behind her, what looked to be an entire battalion of beowolves were dissolving. In the shadows of the trees nearby, a bluish grey troll nodded his approval. "You've grown well. The council has approved your request, by the way. Whenever you're ready, trollmarket will have you." He said, tossing her a faintly glowing orange crystal. Ruby jumped up and caught the horngazel, smiling so brightly that Kanjigar moved around the tree to avoid burning.