Thanks to Bibliophilea for all the help on this! Also posted on Ao3 under Andie_ZIR. I own nothing but Rylie. You'll also find a prompt in here by Corvidprompts on Tumblr.
Rylie had been exploring the Ghost Zone with her mother as a way to get some practice in while her father protected Amity Park. Sam also had some things she needed to do in the Ghost Zone, so it killed two birds with one stone this way.
Things had been going fine, for the most part. Sam had stepped in with weapons from the Specter Speeder when she felt the fourteen-year-old was getting overwhelmed. Which was quite a few times, considering this was her daughter.
Currently, Rylie was about 5'6", covered in soft, snow white fur. Her eyes were silver with white scleras, and she had horns made of pure ice on her head, very pointy and sharp. She had a face that looked more like an animals, with a grey muzzle, big black nose, and a mouth full of sharp teeth. Her white ears were flat against her head as she looked around for another enemy- if there even was one. She had large paws for hands, with opposable thumbs, and stocky limbs. At her fingertips were sharp claws, the same as her feet.
The yeti-looking ghost girl wore a brown cloak that hid most of her body. She still wasn't exactly comfortable with her other half, even all this time later.
Sam looked the same as always, though she was older now. She was 5'4" and in her early 40s, she didn't look a day over 30. Her black hair was down for once, framing her face perfectly. The years of ghost hunting did wonders for her body, and she wore a purple plaid top with jeans.
"Rylie, sweetie, you don't need to keep fighting, you know," Sam said over the Fenton Phones. "You can come in and take a break if you need to."
"Mom," the teen sighed, shaking her head slightly. "I need to be able to protect myself if I get lost in the Ghost Zone."
"I'm just saying, Rylie," her mother replied. "Hold up, sweetie. The scanner is picking something up on that island over there."
"I've got it!" The yeti girl called, speeding off quickly.
"Rylie, wait-" Sam sighed. "Damn it," she muttered under her breath.
Sam quickly found Rylie on the island, the girl looking for whatever the scanner picked up.
The island was actually just two bits of land with a cave in the cliff face. Rylie was at the base of the cliff, undoing her cloak a bit. She felt a bit more at home in the cold weather now. The mother hugged her daughter, pinning her furry arms to her sides. "Rylie, don't scare me like that!" She scolded. "You don't need to handle everything, you know."
"Yeah, but I can handle a lot more things than you can, and dad's not here. I've gotta protect you while he's not here," the girl pointed out, not looking at her mother. Instead, her silver eyes were glued to the mouth of the cave. Something was… Calling her… From inside the cave. A slight glow came from it.
"Rylie, you're still just a kid," Sam pointed out. "You don't need to protect me, I need to protect you. Okay?" She noticed her daughter wasn't paying attention and gently grabbed her face, making the silver-eyed ghost look into the eyes of the amethyst-eyed human. "Okay?"
"... Okay," she sighed. "Can you let go now? Please?" She asked. "There's… There's something in that cave and I'm just feeling like… I need to go check it out."
"Rylie-"
"Mom, I need to. It's calling for me," she begged, looking down at her mother with pleading eyes. "I'll be back out in five minutes, I promise."
"... Five minutes," her mother replied, lowering her hands. "If you don't come back, I'm getting the Speeder and getting you."
Rylie nodded, turning and sinking her claws into the rocks. She quickly scaled the rocks, making it to the cave within about ten minutes. The cave was dark, aside from the glow of… Was that a mirror?
The girl reached out to touch it. It had dusty looking glass that reflected only darkness. It was made with an ectoplasmic version of what looked like brass or bronze. It was decorated ornately, and glowed very faintly. On the back, engraved, was Speculo Inversa.
Turning it back over, she brushed her fingers against the glass. "I wonder what this is…" She mumbled. She noticed a glint on the surface of the mirror, and then the world exploded in a flash of light.
Being thrown from the cave, Rylie crashed into the ground, making an impact crater. The girl groaned, getting up and rubbing her head. "What happened…?" She asked. Her mother was a few yards away, and getting closer.
Suddenly, there was a blast of ice straight at Sam's feet, sticking her in place. "Mom!" Rylie exclaimed, getting up as quickly as she could. Her body was aching, but there were more pressing matters at hand!
… Like the appearance of a ghost that looked eerily like her. Silver fur, blue eyes that were red in the middle, sharper claws… It looked like a scarier version of herself and it terrified the fourteen-year-old.
"Who… Who are you?" Rylie asked, her voice small. "You look just like me, you came from the mirror… But you can't be me…" The girl shook slightly as the other yeti walked closer.
"I am you," the ghost purred. "But I am also better than you." She rose a clawed hand, about to strike down, when Rylie headbutted the ghost. An audible snap was heard as the girl's horns broke off, jabbed into the silver ghost's torso.
"Rylie, get out of here!" Sam exclaimed, using her wrist ray to shoot at the ice. It was melting, but not fast enough. Which meant Rylie was on her own for this fight. "I can handle myself, just go!"
"Not if she freezes you, mom!" Rylie shot back, ice forming in her paws. She shot it out at her copy, eyes narrowed. The ghost dodged, the ice hitting a rock and covering it. "I'll make sure she doesn't hurt you, I promise!"
"Rylie-"
Suddenly, the girl was tackled, the two ghosts going rolling towards the end of the island. They couldn't hear what the woman was saying, snarls filling the air.
"I'll kill you and become you," the shadow hissed. "Just watch."
"I'd never let you become me," Rylie shot back, silver eyes glowing brighter. "I'll make sure you stay in the Ghost Zone!"
The ghost froze up, then started laughing. "You don't know what that mirror did, do you?" She purred with a smirk. "Let me educate you. That was the Speculo Inversa, a mirror that can make copies of whoever looks into it. Those copies are destined to fight the original until one kills the other."
Rylie's eyes widened. "I- I- No!" She exclaimed, shooting her shadow in the chest with an ectobeam to push her back. "I'm not killing anyone! You can just… Just… Go away!" She shot another ectobeam at her copy.
"No can do, Rylie," came the response. A swipe across her back and a cry of pain were heard for miles in the quiet Ghost Zone. "It's you or me, and I'd prefer it to be you." An ectodisc of energy slammed into her back, slamming her into the ground.
She was picked up by the scruff of the neck. "Not going to fight back?" The ghost smirked. "Good."
Suddenly, Rylie phased through the ghost's grasp. She needed to fight back. But she didn't want to kill anyone! The thoughts fought in her mind as she struggled to defend herself. This ghost was embracing her negative emotions, which fueled her powers in ways that made her so much stronger.
How could she kill herself, though?
Another ectobeam sent her flying towards her mother, skidding on the ground and straight into the cliff wall.
"Rylie, run!" Her mother called, frantic. She could easily see the girl wasn't going to fight back, but also wasn't going to give up for whatever reason. She didn't want to see her daughter battered by this mockery. "Get out of here already! Your father will be here soon enough!"
"N- No," Rylie mumbled, getting up. She was leaning against the wall for support, holding her chest in pain. "I- I won't let her hurt you, mom." With that, she ran at her opposite. She wouldn't permanently injure her, but that didn't mean tackling was out of the question.
Right before she reached her copy, the ghost vanished. The silver-eyed yeti stopped, warily looking around. Where had she-
Her world went spinning when she was punched in the side of the head by the silver-furred creature.
Just for a moment, gazing up at her opposite, Rylie thought about giving up.
Stopping.
Dying.
Letting everything end.
It hurt so much. The silver one was hurting her, and everything was awful and it would be so much easier to just give up.
She should've died that night. She shouldn't have become this monster. Not a half ghost like her father, but not a human either.
It's tempting and awful, and she's scared because she actually thinks about it.
But when her foe goes to end it, claws covered in eyes and aimed at her throat, Rylie moved and scrambles to her feet.
"Not today," she hears a voice say from behind her. "Not any day."
Dad.
She feels someone wrap their arms around her body. Looking up, she sees her mother's eyes. She said nothing, gaze moving to the fight going on between her copy and her father.
Her hero of a father.
Her half ghost father.
The man with snow white hair and glowing green eyes in a black and white hazmat suit currently beating that ghost to a pulp.
It was over in a second with him. He ended her quickly and came back to his wife and daughter.
Rylie, finally out of energy, turned human. Just like her father, white rings of energy formed around her waist and spread, turning her human.
The girl had messy black hair, just like her father, and amethyst eyes like her mother. She also shrunk down to a smaller 5'3". She had pale Caucasian skin, wearing a white blouse with a black tie and black slacks.
"Hey dad," she mumbled, her eyes half-lidded.
"Hey, kiddo. We're gonna get you to Frostbite's, okay?" He asked softly, taking her from his wife. They all boarded the Specter Speeder, which had been left on the other side of the island
It was a few minutes into the trip, with Danny making sure Rylie was okay, when the girl spoke again.
"Daddy?" She asked.
"Hm?"
"H- How'd you know I was in trouble?" She hugged his gloved hand closer, savoring the cold energy that radiated from it.
"Don't you remember? I can feel it," he replied.
"... Oh yeah, I forgot about that."