Wildfire

I posted Phoenix's arson story as an unformatted text wall, here it is for those who missed it

 Phoenix was a sullen, troubled teenager and developed a number of unhealthy coping mechanisms. Smoking, shoplifting, vandalism.....setting stuff on fire. It started off harmless enough. Burning garbage, her report cards, stuff that wouldn't be missed. One night, after yet another explosive argument with her mother, she sneaks out for a prowl around town....and happens upon an old abandoned shed. 

The windows are broken, the wood is rotting with age. Deep within, she feels the familiar flicker of excitement, the urge to burn. So she sets it alight, and it burns. And burns. And right when it looks to be petering out....a dry, overhanging branch catches fire. 

Phoenix doesn't panic at first, she gets to work putting that out, but it's spreading a lot quicker than you'd think. She's so busy with this she doesn't notice the dead grass around the shed catching aflame. The bushes going up in smoke. So much smoke. It's getting hard to breathe. Hard to fly....and just like that, an inferno comes roaring to life. 

The wildfire tears through the forest, engulfing trees, turning the night sky a hellfire red. Phoenix can't put it out. It's moving too fast, heading right.....toward Fluttershy's animal sanctuary. Oh no.        

Terrified, Phoenix fights her way through the smoke and heat to get to the bell that sits atop Ponyville's town square. She kicks it and kicks it until she collapses, managing to rouse all of Ponyville. Phoenix passed out before she could see the weather ponies rushing in with rain clouds- and fortunately, the fire is put out in time. Fluttershy's family, home, and animals are safe, and her sanctuary is not too damaged. 

But Phoenix wakes up to a whole new WORLD of trouble. For one, her parents are FURIOUS, both at what she DID and the fact that she very could've very nearly DIED.....Dash is so angry she can hardly speak. Nix has never seen her mom cry before. Phoenix is charged with the crime of arson, and sentenced to a stint in a juvenile detention facility. She's so rattled by the experience that her rebellious inner fire fades away into nothing. She becomes withdrawn, quiet, depressed, and badly misses her family. Partway into her sentence, Princess Twilight proposes trading the remainder of Nix's time locked away for entry into a youth behavior reform program. Rainbow, Dumbbell, and the authorities agree to this plan, and Nix is placed into what is more or less boot camp, under the Royal Guard. 

Although she initially hated the training, studying, rules, and public service expected of her, Nix eventually began to adjust and flourish under this strict discipline. (This is also how she got so jacked). She finishes out her schooling in Canterlot and trains to become a blacksmith for the royal guard, eventually finding her calling in forging weapons and armor. As an adult Phoenix still has a bit of her old rebel streak, but she's a lot more relaxed, and better at managing her once turbulent emotions. Although Auntie Fluttershy has mercifully long-since forgiven her, and she maintains a good relationship with her dad and Cloudy, her relationship with Stormy is tense and rather bitter (Nix has always felt second best in regard to her big brother, Stormy remembers Nixie's cruelty and doesn't trust her). 

Her relationship with Dash is the worst of all. Phoenix is secretly very ashamed of the disgrace she's brought to her mother's legacy, and covers this up with hostility and avoidance.