A/N It is my headcanon that Caitlin sneezes snow.

Caitlin stood in the cortex, finishing off some work unfinished, it was just her in Star labs, well, her and someone else,
"Hey Caitlin?" Asked Ralph.
"Oh, God you scared me Ralph!" Caitlin shouted.
"I need your help with something."
"What is it?" Caitlin asked.
"Well, since no one has bothered to decorate Star labs, again I need your help to decorate."

"And why me?"
"Because well.."
"Well?"
"Can you just help please!?" Ralph shouted.
"Okay then." Caitlin answered.
"Thank you!" Ralph hugged Caitlin.
"Your welcome I guess." Caitlin replied
"Get here before everyone else okay?"
"Okay then."

Caitlin arrived at Star labs 1 hour before she would normally get there, she was greeted by Ralph in his Santa costume from last year.

"Nice sweater." Ralph complimented Caitlin's red and white striped sweater.
"Nice costume, Strechy Claus."
"Thanks. Well let's start decorating then."
Ralph and Caitlin decorated the entirety of Star labs, from misteltoe to tinsel.

"One last thing now." Ralph said.
"What's the last thing?" Caitlin asked.
Ralph grabbed a pepper shaker and shaked it in front of Caitlin
"Ah-choo!" Caitlin had loudly sneezed inadvertently covering Ralph in snow.
"Snow." Ralph replied.By the time Barry and Iris would normally get here Ralph and Caitlin had covered the entirety of Star labs with snow.

"How long till Everyone arrives?" Ralph asked.
"I have an idea" Caitlin answered as she pressed the emergency button on her phone.
Before Ralph could do anything Barry had arrived in Star labs in his Flash suit.

"Merry Christma- choo!" Caitlin sneezed.
"Her idea, not mine." Ralph justified.
"Are you kidding me!?" Cisco shouted as he walked into the cortex.
"Merry Christmas." Caitlin replied.

An hour had passed and everyone was enjoying themselves, although Caitlin was still sneezing snow from time to time."Are you kidding me?" Cisco laughed catching everyone's attention.
"What is it Cisco?" Caitlin asked.
"Look who's under the misteltoe!" Cisco replied.
Caitlin realised she was under the miseltoe with Ralph.

"Oh, God." Caitlin exclaimed.Before Caitlin could add to her sentence Ralph had sealed a kiss.
Caitlin normally would've pulled away but, miseltoe rules.

That was one of the best Christmases Caitlin ever had.