A/N: Hey guys! I was watching the end of season three again recently, to get ready for season four, and this idea popped into my head. I hope you like it!

"I'm not Caitlin anymore."

"You're not Killer Frost."

"No, I'm not. I'm something else. And I need to figure out what that is. On my own."

She walked away from them quickly, so they couldn't see her face. She hadn't expected to feel so strongly about leaving them. She knew she had access to all of her emotions now, but she hadn't thought she would feel them as deeply as before, at least not yet. When she'd first woken up as Killer Frost, after Julian had ripped off the necklace and saved her, the emotions she'd understood as Caitlin Snow had been lost on her, aside from rage. She had definitely felt rage, and all the darkest emotions that, she now realized, she hadn't truly understood before becoming Killer Frost completely. Hatred, jealousy, lust for power. All of those had been perfectly clear to her.

Because she really had become Killer Frost. All the struggles to keep that part of her inside only made the meta want control even more. Once the necklace had been off, with her defenses down, the meta instincts completely took over. She hadn't felt any affection for her teammates. She'd seen them as if through a fog, pestering shapes running from her in terror and pleading with her to come back to her senses, and become Caitlin.

"Caitlin, you can fight this." Barry said.

"I know." She responded with a little sneer. "But I don't want to."

Killer Frost didn't care about Team Flash. She only wanted power, freedom, and a little bit of destruction.

But after those first few days, a little bit of Caitlin Snow started to come back, sneaking into the crevices of her mind. She could have killed at least one of the members of Team Flash, but she settled with wounding them instead. It was easy to let the cold rage control her when they were face to face, when she could let their words disappear unheard. But after the battles, when she was alone or back in Savitar's lair… that was when the little bits of her that were Caitlin Snow made themselves known, fighting to become part of her again. And every time she became a little less Killer Frost and a little more Caitlin Snow, until she started actually struggling with the two identities.

"Caitlin, I love you." Julian said.

"I don't love you, Julian. I never did. I never loved any of you."

Saying that to him, to all of them, had taken every effort she had. It had weakened her control enough for her to feel the Caitlin part of herself take over, just for a second. And once that happened, she had no idea who she was.

She stayed with Savitar, because it made sense. She was Killer Frost, right? She had to be. She still looked like her, and she certainly wasn't the woman she was before. But she didn't feel like Killer Frost. There was only one moment when she felt like she knew who she was:

When Savitar tried to kill Cisco.

In that instant, she was both Caitlin Snow and Killer Frost, because both of them agreed that Savitar had to be stopped. They had different reasons, but the action was the same.

There was a rush immediately after saving him, a warmth running through her. In that moment she regained access to everything that had defined her as Caitlin.

Except she still didn't look like Caitlin. Her eyes were brown again, but her hair was still that snowy white. She was a mixture of both. And she had no idea what that made her. How much of Caitlin should she be? How much of Killer Frost?

One thing she was absolutely positive about was that she needed to keep her powers. She'd just given the cure back to Julian, because she couldn't use it.

It was almost funny, she thought as she walked away from the team. She'd spent months agonizing over the fact that she had powers, and not being able to control them. Months searching for a cure, terrified of what would happen without one. And now that she had a cure, she wanted nothing to do with it.

She wasn't sure of her identity, but those powers were a part of her now. There was no going back to Dr. Caitlin Snow, normal human. She was a meta.

She was walking into her apartment when she realized there was someone already inside. The lights were off, as she'd left them, but her door had been unlocked. And she was always careful to lock it. She stopped with her hand on the doorknob, readying herself, and strode into the room with her hand raised.

"Who's there?" she asked in her most demanding tone.

"A friend." A familiar voice said.

She looked up as Cisco turned on her lamp, shocked.

"I wasn't trying to be that creepy guy in the movies. I just got here and couldn't find the light. You move everything around? I swear it was in that corner last time."

She lowered her hand with a sigh, letting her powers sit. "What do you want?"

"To see you." he said, and it was so simply Cisco that she felt a twinge for going on the offensive. "Caitlin – are you going by Caitlin again, or…?"

She looked at him steadily, still not moving. "Yes," she said quietly. "I'm going by Caitlin." She saw the way his expression lightened with this small piece of information. "But I'm not -."

"I know." He interrupted. "You're not our Caitlin anymore, blah blah blah. That doesn't matter." He held her gaze. "We need you, Caitlin. However you define yourself. We just got Barry back, and you're the last piece of the puzzle. We can be a team again."

She heard the longing in his voice and found herself genuinely considering going back with him. She would be doing what she loved: using science to help keep people safe. She would be with the people she saw as family. And maybe she would be able to go into the field from time to time, and actually fight the other metas.

"Alright."

The grin that split his face actually made her chuckle, and he was hugging her before she really knew what was happening.

"You might not think you're our Caitlin, but you sure seem like her." He said. He opened a portal and held out a hand to her.

But she hesitated. She hadn't seen anyone from the team for months. What would they think, seeing her just walk back into their lives? Would they hate her for allying with Savitar? Would they pity her for having become Killer Frost so completely?

"They all miss you, Cait." Cisco said softly. "We all just want you home."

Caitlin swallowed and nodded, taking his hand.

At first they were hesitant. She saw that clearly, though she showed nothing on her face. Initially they hugged her and smiled, telling her how great it was to see her again. But once that was done, and they were really looking at her, she knew they were wondering. Was it really Caitlin?

She looked like her old self now. Her hair had returned to its steady brown, her eyes the same. Until she used her powers, that is. Then her eyes turned a light blue. Of course they didn't know that, though. They hadn't seen her use her powers yet, not since rejoining the team.

Like Barry and Cisco, she used her powers frequently. Mostly for trivial things, like cooling a drink in her hand, but occasionally she let herself enjoy them more. She'd frozen a park a few times, to see how much damage she could do to it structurally. To more adequately understand her limits, of course.

So the first time she used her powers in front of them, to refreeze an ice pack for a twisted ankle, she wasn't surprised by their expressions of shock and unease. She'd hoped they wouldn't react that way, but she'd expected them to.

"Your eyes change?" Iris asked.

"When I use my powers." Caitlin said. "Yes."

"Does your hair change too?" Wally asked.

"Not in a long time." She said, and walked away. There was one question no one dared to ask. She thought they knew the answer, but apparently they didn't completely trust her control, with how strongly they reacted to her power usage that first time.

Had she killed anyone.

No.

That murderous rage that had awoken inside her when she first became Killer Frost hadn't been rekindled, and she was glad of it. It was the thing that let her confidently say that, primarily, her identity comprised of Caitlin Snow. She certainly got angry. Much more easily than she used to. But not like that.

…

…

Not yet, at least.

She started helping the team fight metas, when the opportunity came up. Just a small assist here and there, but it made her feel more useful than she ever had, being able to help them fight and then patch them back up after. Until the one time she had to be patched up, which kind of stunk.

There was one meta human that kept giving them trouble. Timothy Fords. He seemed to be able to manipulate energy, sending straight waves of it at people or even sapping some from them. But he only wanted to fight. He'd cause some sort of disturbance to get their attention and then fight with them, and either gain the upper hand or leave before he could be captured.

Cisco was calling him Houdini, since he kept vanishing before Barry could catch him.

"But he uses energy powers." Barry pointed out after Cisco officially named him.

"Yeah, but he's an escape artist. I can appreciate that."

"So glad you're a fan." Fords said, walking into the cortex.

Caitlin, Barry, and Cisco whipped around.

"Seriously?" Cisco asked. "How come our security never works?!"

Barry raced for Fords, phasing through the energy attack that was sent at him. Fords waited until Barry reached for him and touched his arm, sending Barry slamming into the wall.

Caitlin hesitated while Cisco and Barry struggled to beat Fords. They hadn't come up with a strategy to capture him yet, because in the two times they'd fought, the battle had only lasted a short time. They didn't know the extent of what he could do, or what would be effective against him.

A loud bang tore her out of her quick analysis, and she saw both Cisco and Barry hurled against the desk, crashing through it. Cisco had a dazed look on his face, and Caitlin worried he'd hit the desk and floor too hard. And now he was under debris.

Barry jumped back up and started running, summoning lightning. Caitlin tried to distract Fords while Barry worked up the charge by sending an icicle at him, but he dodged it without concern, looking at Barry.

The lightning was thrown from Barry's extended arm, arching over to Fords – but Fords smiled and thrust out his hand. The lightning doubled back on itself and struck Barry, who yelled and fell back. They hadn't expected Fords to be able to do that. Fords followed the rebounded lightning attack with another beam of energy, and Barry slumped to the ground.

Caitlin realized she was the last one standing. Joe and Iris were out; Wally was visiting Jesse… Fords had surprised them. That was the only reason he'd managed to knock out Barry. But it didn't change the fact that he had, and she was alone now.

Fords looked at her with an amused expression, slowly walking closer to her. She looked around, but it wasn't a reassuring sight. Barry was unconscious, Cisco trapped and hurt. Neither showed signs of being able to help. She shook out her hands nervously, feeling their temperature drop as she prepared to use her powers.

"Are you gonna try to make me slip?" Fords asked with mocking concern. "That ain't gonna stop me."

"You can still surrender." Caitlin said, her voice strong. "I don't want to hurt you."

"And you won't."

Fords lunged with his energy attack. Caitlin shot a jet of ice at him. The attacks collided between them, cancelling each other out. Caitlin spread a thick covering of ice on the floor, sweeping it under his feet to trip him up and launching another attack at his core when he moved. But Fords jumped when he saw her ice coming on the floor. Her attack passed him by, and he shot a beam of energy at her from above. All of this happened in a few seconds, so that by the time Caitlin realized she had to defend herself, it was too late to dodge or make a shield.

She was thrown back, skidding to a stop against the wall. Fords was grinning. "The kid with the glasses packs more of a punch than you do, and that's saying something." He was walking closer, with slow, confident steps. "I thought I recognized you." he said in a slightly different voice. "You look different, but you're that Killer Frost, right?"

"No!" She recovered her breath and sat up, sending spikes of ice at him. He dodged them carelessly and hit her with another energy beam, making her wince in pain.

"I thought you were so impressive when I first saw you." Fords said. "You were so much stronger then. Not afraid to use your powers."

"I'm not afraid." Caitlin said, standing up. Her hands were shaking. She was getting angry.

"You seem like you are. I think you're hoping someone else will come and fight me, so you can just go on kidding yourself that you have control. But no one's coming, Frost. And I want to see some action. I want to fight the famous Killer Frost."

She knew he was goading her into attacking, but her emotions got the better of her. She went after him with a yell, her powers on their highest level. He said she was scared? That she didn't have control? She'd been using these powers for months! She knew how to command them! Maybe she hadn't wanted to hurt him at first, but she wanted to now. He had hurt her friends without care. And he wanted it.

So she went on the offensive, the speed and ferocity of her sudden attack wiping the smile off Fords' face as he backpedaled to avoid her blows. She hit him center mass, freezing him against the far wall with a thick coating of ice, and leaned in close to his face.

"I'm not Killer Frost." She said, her gaze burning into his.

Fords had the nerve to actually smile. "Sure look more like her now. But you're right. You've never killed anyone. You're too weak."

She thrust one hand on the ice covering his chest, the ice hardening at her touch and making him grunt in pain. "You want me to be stronger?" she asked in a dangerously soft voice. The blood was roaring in her ears. "You'll wish you hadn't."

And she placed her hands on either side of his face, watching his skin turn blue and start to crack as he stared at her in plain disbelief and fear, screaming.

The screaming had stopped before she let her hands fall back to her side. Fords was frozen, his expression stuck on terror. Caitlin almost smiled as she said "told you."

"Caitlin."

She turned at Cisco's groan and voice. He focused on her with difficulty, his head wound no doubt making it hard. "Caitlin, what did you do?"

The rage that had still been fueling her abruptly faded, leaving behind a growing sense of horror. She looked at Fords and saw how still he was. How much damage she had done. She didn't know if he was alive.

She turned back to Cisco, running over to free him, but he recoiled when she approached.

"Cisco -."

"Your eyes." He said, looking fearful. "You look like her."

But she'd stopped using her powers. They should have gone back to being brown by now. She freed him from the debris silently, refusing to acknowledge what he was saying. She had to help Cisco and Barry, and be a good doctor.

A hand caught at hers as she started to walk away to get her med kit. Cisco. "Cait, is Fords…"

"I don't know!" She said quickly, her voice rising. "I didn't mean to – I couldn't stop myself from -." Her eyes travelled unwillingly back to Fords, and she felt the truth of it settle over her. "What have I done?" she whispered, horrorstruck.

She tore her hand away from Cisco's and ran to the door, knowing she had to leave, to get out of there as fast as she could.

"Caitlin, wait!" Cisco yelled.

She kept running, out of Star labs and onto the street, knowing she wouldn't be able to run in a minute. Her body was already shaking.

She made it to a tree and collapsed on the ground, sobbing and clinging to herself. She had killed someone.

All that time she'd been Killer Frost, she'd never actually done it. The months after, fighting with herself over which identity she should assume, she'd fooled herself into thinking she was normal again. But obviously she'd lied to herself. She hadn't lost control back there. Not in any excusable kind of way. She'd wanted to hurt Fords. Badly.

The grass around her turned white as it was coated in frost and ice. The pond crystallized, and she dragged herself over to it, looking at its surface.

Brown hair. Blue eyes.

She tamped the flow of her powers with difficulty and watched for the change, knowing in the pit of her stomach it wouldn't come. Minutes passed, and still her eyes stayed that pale blue.

She thought it was permanent now. This was who she really was. She couldn't try to be just Caitlin any more than she could try to be just Killer Frost. The last few months had been a tease, a temporary fix. Now she had to accept both parts of her nature, instead of trying to pick the best from each. She had to be a meta.

A sort of Caitlin Frost.

She didn't know how long she sat at the edge of that pond, staring unseeing at her altered reflection. Now that her initial shock at having killed someone was passing, she was processing it calmly. At least, externally she was calm.

All she kept thinking in her head was that she was a murderer.

That was how Barry found her, lost in the aftershock in the frozen park. She saw him for a few seconds, looking at her, and then she was being picked up and rushed back to the lab. Barry set her down in the damaged cortex, staying close with his arms outstretched to apparently catch her if she fell. But she could stand just fine.

She looked at where Fords had been and saw that he was gone. Cisco was leaning against the wall, his arms crossed.

"Caitlin," Barry said softly, demanding her attention. "Did you lose control? Did Frost take over?"

She swallowed thickly. "I wish I could say she did."

Her voice sounded kind of hollow to her own ears. She saw Cisco's expression change to greater concern.

"Killer Frost is part of me." She said. "I keep trying to pretend she's not, that I can just use my powers and act like I used to, but I can't."

"You're still adjusting." Barry said. "It's okay to -."

"To what? To kill someone?" she asked, her voice rising dangerously.

"It was a mistake." Cisco said. "A bad one, but still a mistake. We all struggled with our powers at first."

"But you didn't kill anyone!" she yelled, her breathing ragged. Maybe she wasn't so calm after all. But they didn't understand. "You never went dark, Cisco! You don't have this kind of darkness in you, like I do!" She took a rattled breath, her voice coming out a broken whisper. "You've always known who you are."

"Cait -." Barry started to say, reaching out a hand.

Cisco pushed himself off the wall and walked over to her, determined. "And I've always known who you are. You're a dedicated, loyal woman who always looks out for the ones she loves. You're insanely smart and quirky and awkward, so you fit in great with us. You're the heart of this team, and my best friend." He locked eyes with her, his expression completely serious. "You're still that person, Caitlin. Yeah, things have changed, but not as much as you think. And maybe I didn't struggle like you have, but that doesn't mean anything."

She searched his face for any sign that he was lying, just trying to make her feel better, but he looked more earnest than he ever had before. She was trembling slightly as she wrapped her arms around him, leaning her head on his shoulder. He held her tightly, and she felt Barry's comforting hand on her shoulder.

"It's gonna be okay." Barry said softly.

She didn't feel okay, not yet, but she believed she would eventually. "I'm sorry." She said.

Both boys tightened their grip on her. "We're a family." Barry said. "We'll figure this out."

Caitlin nodded against Cisco, and they released her. She looked at them and saw that they were taking in her change in eye color, realizing it wasn't a glow that meant loss of control, but a permanent change. Which meant they hadn't noticed before, because they'd been concerned with other things.

It made her love them even more.