"Come on Caity, we've got to get these outside before bedtime."

Caitlin zipped up her winter coat. "Why are we putting water bottles outside?"

Her dad looked at her with a reserved, happy smile. "Science."

Caitlin started to smile too. It had been a while since they'd done a science experiment together. It had been ages since they'd done their game with the periodic table of elements. She pulled on her boots and practically ran to the door. "Come on, come on!" she cried.

Her dad laughed and grabbed the four water bottles from the counter.

"Don't be out too long," her mom said, standing by the living room door. "It's getting cold."

"Which is exactly why we can do this," her dad said. "Open the door for me."

Caitlin pulled it open and followed her dad through it, pulling it closed behind her. It had been cold the last few days, and tonight felt especially chilly. Caitlin pulled her coat tighter against her and looked at her dad questioningly. "What do we do now?"

"We put the bottles in the snow."

"But there's only two inches."

He handed her a bottle. "That doesn't matter. The important thing is the temperature tonight. It's above freezing now. Just barely, but it is. By morning, it'll be below freezing."

"So what's going to happen?" she asked, placing the bottle in the snow by the porch.

He put down a bottle, and handed the other two to her. "What's your theory?"

Caitlin grinned, glad he wasn't just telling her. She wanted to make this a full experiment, which meant a hypothesis. She placed the final two bottles, spreading all of them evenly apart, and ran through the periodic table – the real one – in her head. This was more chemistry than biology… she started going over properties of water, and looked at her dad with slightly narrowed eyes. "Water bottles fill with ice when the temperature goes below freezing. It seems like it should just freeze."

There was something in his eyes that she couldn't read. It looked like he was happy with that answer, but why would he make a big deal of this if they were just making ice? "There's something you're not telling me," she accused.

"Yes," he said plainly. "Hopefully you'll see when we check these in the morning." He walked back to the door and held it open for her, and Caitlin reluctantly walked back inside.

She didn't stop thinking about those bottles until she fell asleep that night, almost an hour after her bedtime. Even with all that time trying to figure out what her dad wanted her to see, she couldn't think of anything besides the water freezing.

So when she woke up the next morning (early, because her dad said an inquisitive mind meant an early riser), she bolted out of bed, determined to go and see the bottles. She knocked loudly on her parents' door and ran to get on her boots and coat. By the time her parents walked into the kitchen, Caitlin had been waiting five minutes fully dressed to go outside. "You're still in your pajamas," her mom said.

"We've got science to do," Caitlin told her seriously. "Getting dressed can wait."

Her mom chuckled, and her dad walked up with a smile. "Let's go see if our experiment worked." He stopped with his hand on the door. "What was your hypothesis again?"

"That the water will have turned to ice," Caitlin recited.

Her dad opened the door. "Let's find out if you were right."

It was colder than it had been the night before: the kind of cold that you felt in your chest whenever you took a breath, but Caitlin barely noticed. She ran to where they'd placed the bottles and crouched down to look at them. They looked like they had the night before. They definitely didn't look like they'd frozen, and she couldn't hide her disappointment as she looked up at her dad.

"Pick one up," he said.

He didn't seem disappointed… they weren't supposed to be frozen, she realized. She reached out and grabbed the bottle closest to her, bringing it closer to her.

"Bang it on the ground, and watch closely," her dad told her.

Caitlin tapped it on the ground, staring at it. As soon as the bottle hit the ground the water started to crystallize, turning to ice. She watched as, in a matter of seconds, the ice travelled up from the bottom of the bottle. When it reached the top she turned the bottle upside down, her mouth open in amazement. It felt much colder in her grip, and when she squeezed it, the bottle crackled. Definitely ice inside now.

"How did it do that?" she asked.

"You just super cooled water, Caity," her dad said, walking up to her. He picked up another bottle and hit it on the ground, making that one freeze as well. Caitlin looked from the bottle to her dad, fascinated.

"You said it was below freezing last night."

"It still is," her mom said, from where she stood on the porch. "It's just below freezing now."

"So how did they stay liquid?"

"We took pure water, in a sealed bottle, and let it adjust to the natural temperature. The temperature changed so slowly that the water didn't change phase. Moving it around, like when we banged it on the ground, allowed the ice crystals to form, and since the water just realized how cold it was -,"

"It froze more rapidly," Caitlin said, smiling as comprehension dawned on her. "That's incredible."

"Bring the other two bottles inside," her mom said. "I'll get a bowl and water."

"Why?" Caitlin asked.

Her dad gingerly picked up the bottles, not moving them very much. "We're gonna try to make an ice sculpture."

Caitlin followed her parents inside, her thoughts running fast. Her mom put a big bowl with a little water in it on the kitchen counter, and dropped an ice cube in it. She nodded at Caitlin's dad, and he uncapped one of the water bottles and looked at Caitlin. "Watch the ice cube."

He poured the water from the bottle into the bowl, and Caitlin almost laughed. When the water from the bottle hit the ice cube in the bowl, it froze, making a lumpy mess of ice. Her dad moved the bottle around, shaping the little ice sculpture.

"Why did it freeze?" he asked when the bottle was empty.

"It started when it hit the ice cube," Caitlin said, staring at the ice in the bowl. "The ice was below freezing, so when the water hit it… it automatically started crystallizing and expanding."

Her dad rubbed her shoulder, grinning. "There's my little scientist."

"Caitlin, you make the last one freeze," her mom said.

Caitlin didn't hesitate, stepping forward and carefully opening the water bottle. She moved it with a precision she knew most eight year olds didn't have. She decided to go for height with her ice sculpture, and ended up with a structure that almost looked like a castle. "Awesome," she breathed.

"You just made an ice sculpture, Caity," her dad said warmly, wrapping his arm around her shoulders.

Caitlin stared at it, entranced. "Ice is beautiful."

The memory played over in her mind as Caitlin looked at the four satellites Cisco now had control of. She hadn't thought of that day in a long time; even when she'd first started using her powers, making ice without relying on the temperature outside, she hadn't remembered that day. Then again, she hadn't thought Frost had any connection to her past before. She now realized her dad had probably known about Frost, when he'd done that experiment with her. Maybe that had been why he taught her so much chemistry at such a young age.

She stared at the monitor, knowing Cisco was looking at her questioningly. Waiting for her to say she wanted to find her dad.

Caitlin took a deep breath, pushing the memory away. There was no point in dwelling on the past, when she could find answers in the present. Thomas could tell her everything she needed to know, when she saw him again. "Alright," she told Cisco. She met his eyes with a determined nod. "Let's find him."

A/N: Super cooling water is a real, awesome experiment. I've done it once, and it's weird but cool. I thought about it the other day, and thought it would be a fun thing for a somewhat fluffy oneshot with little Caitlin and her dad (plus, it involves ice... I couldn't resist making it seem a little bigger than just a fun experiment with dad). I'm super excited to learn more about Caitlin's past. Hope you liked this.