A/N: I believe this is one of the darkest things I've written to date (not saying much, I don't write a lot of dark stories, but…)

This is really anything but fluff, and yet… it kind of is, at times. I thought of this story idea the other day, about Caitlin dealing with everything after she manifests the Killer Frost powers, with a little help from Elsa. It's written from Caitlin's point of view, mostly from inside her mind.

I do have to throw in a warning - this deals with kidnapping, death, anxiety, all sorts of things that may cause triggers in people. There's no super-gory details or anything, but it may still disturb some people.

I do not own either Frozen or Flash. If I did, I'd be running either the CW or Disney, and would have no need to write fanfiction. Everything I do is for fun and experience rather than profit.

Cold. That's all she could feel. Ever since the night she'd been kidnapped, she'd felt cold. She'd roll herself in quilts every night, even in the middle of the summer. Even Barry's speed couldn't help her. Cisco had tried too, but everything he'd created had failed. Even Ronnie, with nearly infinite heat, could only help for a few minutes. He'd failed. She'd failed. She'd become a monster. She could still remember the faces of the men who'd grabbed her as their hearts turned to ice and shattered.

"Ronnie!" She shrieked as the men surrounded her and began forcing her into the van, only to remember that she'd gone out alone. She must have been knocked out by something, as the next thing she remembered was waking up alone, gagged and bound in a basement, or an attic. She couldn't tell. Soon, she was joined by one of the men. They removed the gag and the bindings. "You can't leave, so why not?" They said, smirking. They left her alone after that. Food was given to her once a day, or maybe once every few days. It was dark in that room, with only a sliver of light making its way in through a cracked ceiling beam. She could sometimes hear people elsewhere in the building. Days began to run together, turning into weeks. She wondered if the boys had given up looking for her. Maybe they thought she was dead. Maybe they didn't care. She sat in the corner, refusing to cry. When she finally gave in, the tears felt colder than normal, more like ice than warm drops. One of the men walked in then. She could smell alcohol on him. She could hear his friends cheering him on from outside the room. Then he grabbed her. Before she could scream, something happened. He stopped, and began to struggle for breath. Stumbling back, he clutched at his chest. "Why?" was all he could ask before he collapsed. His friends rushed in then. They stopped once they saw the body, with her standing over it. Something snapped in her then. She reached for the men, and immediately saw their faces contort in pain as they began to shiver. They all reached for their hearts as they collapsed. She fled then, feeling warmer than she'd been in days, yet terrified of herself. She'd killed five men in cold blood, and wasn't even sad about it. Seeing a forest in the distance, she ran towards it, looking to disappear for a time, until she could determine what she had to do.

She'd returned to Central City eventually. She'd been gone for nearly four months, apparently. Funny how time flies. When she returned, she immediately became reclusive, not even allowing Ronnie to touch or come near her. She stayed in her apartment, wrapped in quilts, drinking cocoa. Eventually, she'd explained her problem to Barry and demonstrated on a glass of water. By now, she could actively create ice as well as suck heat out of items. He and the others had tried to help. Cisco had even come up with a name for her. "Killer Frost." Why it had to sound so evil was beyond her. Maybe it fit. She couldn't think of herself as anything but a villain.

Then Barry showed up at her apartment one day, nearly six months after she'd returned. Apparently he'd done some universe and time-hopping with Cisco's help, and brought someone who could help. A young woman appeared behind him. Barry left after introducing the woman as Elsa, and the two women began to chat. Elsa had the same abilities as her, which she demonstrated to the doom of a glass. With some prompting, Elsa began to relate her story. She'd injured her sister, Anna, as a young girl, forcing her family to have Anna's memories removed. As Elsa grew older, her powers only intensified, as she locked people out of her life. Eventually, their parents had died. They stopped for lunch at this point, where Elsa taught her the basics on how to not leech the heat out of everything she touched. Cold cocoa had only so much appeal, after all. After lunch, Elsa continued her story, explaining how the townsfolk had learned about her powers, how she'd nearly killed people, and then run away. Elsa choked up at this point, explaining how she'd frozen her sister's heart when she came looking for her, and how her sister had risked her life to save Elsa, nearly dying in the process. They'd realized that love was the only cure for the freezing. Finishing her story, Elsa looked at her pointedly. "I can teach you to control it, but you need to let people back in," she said. They shook hands at that point, with Elsa promising to come back the next day to hear her answer.

Could she learn to control it? Could she let people back in? What if she killed them, just like those men? Falling back into the quilts, cocoa, and guilt Elsa had dragged her out of, she laid there and shivered until she finally fell asleep.

Waking up the next morning, the room seemed warmer than normal. Walking to the kitchen, there wasn't a trail of ice left behind. Perhaps everything had just been a bad dream, a nightmare now passed.

Then she looked in the mirror. Her once brown hair was tinted white at the tips, and her eyelids and lips were a slight blue. A knock at the door was followed by the entrance of the woman from the night before. Elsa, her brain supplied. Elsa took one look at her and immediately gave her a hug, despite frightened and negative responses. "Don't worry, cold doesn't bother me." She whispered. They stood there for a minute before Elsa pulled back and looked at her. "I suppose we should begin before the cold spreads further." Elsa pulled her out the door and down the stairs, despite protests relating to the facts of no breakfast and still in pajamas. Elsa sighed and turned to her, waving her hand to create a mid-length dress, appropriate for both work and town, while knowing the real issue behind the protests. She was afraid she'd hurt someone, a feeling Elsa knew all too well, but letting her give into that fear was the worst possible thing to do. They caught a bus to downtown, grabbing lunch at a restaurant. Elsa kept the mood light, avoiding unnecessary crowds, avoiding any possibly stressful situations. The two women spent the day window shopping, despite anxiety and concern from one of them. They bonded over cupcakes and coffee, with Elsa promising to stay as long as she needed her.

And she did. Elsa came back every day for two weeks, soon becoming her best friend. Eventually, Elsa convinced her to try going back to work. All three of her co-workers were surprised to see her, with all three giving her a hug at the same time, despite her stiffening in fear. She was still afraid that she'd hurt one of them, freeze their hearts. She caught Elsa's eye, and Elsa smiled reassuringly. She wouldn't hurt them. She could control it. She wasn't a monster. She wrapped her arms around her co-workers, her friends, returning the hug. She didn't necessarily feel warmer physically, but she felt warmer emotionally than she had in months.

She continued to go to work every day, still visited with Elsa to learn how to control and use her abilities properly. Slowly, she began to return to normal life. She knew Elsa would have to return back to her own world eventually, and a few weeks later, almost two months after she'd arrived, Elsa said it was time for her to return. "I've left Anna in charge far too long as it is." Before Elsa went, she left her with a necklace in the shape of a snowflake, and some final words. "As long as you keep people around you, keep love in your heart, it will never freeze." Elsa left with Barry then, leaving her sad, but in a far better place than she had been two months ago. She'd finally moved past those five men she'd killed. While she'd always have it on her conscience, she wasn't a monster anymore. She was Killer Frost, yes, but Ronnie, Barry, Cisco, all her friends… they'd never let her heart freeze, as long as they were alive.

"Ready, Frost?" Flash grinned at her, ready to save Central once more. Vibe was on the other side of her, and Firestorm was on the other side of him, both also grinning away. She smiled back, feeling warm inside. "You'd better keep up," she laughed, darting away on a wave made of ice. They wouldn't fail her, and she wouldn't fail them.