A little story i came up with one night. I wrote it quite late so please forgive me for any mistakes.
This prompt was mainly inspired by Lucifer 1x9

It was late in the evening.
Everyone went home and it was just Barry left in the lab, or so he thought.
He went to a room he had recently discovered, the place was so big even after five years they still didn't know everything.

In this room he found a piano, thanks to his super speed he was able to learn it in no time.

So this one night he was sitting at the piano playing 'knockin' on heaven's door'.

Caitlin meanwhile was in her lab finishing some tests when she heard the music, curiously she followed the noise until she saw Barry sitting there with closed eyes, a huge smile on his face. She stood in the doorway and watched the speedster play.

After he finished he opened his eyes to see a clapping and smiling Caitlin. He immediately shot up rubbing the back of his neck a bit embarrassed.

"Hey." He said nervously.

"Hey, that was really good."

"That was alright i guess."

"It was a lot more then alright, Mr Allen." She laughed.

"I've been coming down here whenever I had the time, try and shift my thoughts from cicada."

Caitlin sat down next to him and gave him a hug. One which he gladly accepted, he could sit here for hours holding her.

"Do you play?" He asked curiously pointing at the instrument.

"No." She bit her lips and immediately Barry knew she was lying.

"Come on, you must know something." He grinned.

She let out a quick sigh. "I've had a couple years of lessons before I decided I wanted to become a doctor. I don't really remember anything."

"Cait, I know you, you don't easily forget anything."

"Fine" She laughed before putting her hand on the keys. "The only thing I remember is..."
She started playing 'Heart and soul' by Hoagy Carmichael. A smile on her face that made Barry's heart melt.

"You're joking" He said.

She shook her head, still smiling and playing.

"Alright" He said and then started accompanying her.

After they finished they laughed and looked at each other.

"You are a superhero, you can dance, sing and play the piano. Seriously what can't you do?"

"Well there is one thing."

"What is it?" He was hesitating for a while and trying to avoid the question. "Come on, you can tell me, it can't be that bad."

"The one thing I can't do is confess my feelings to the woman I love."

Caitlin immediately felt her stomach drop. She had feelings for him for so long but never acted on them. She was afraid that he didn't feel the same way and that if she said something it would end their friendship. She knew he only liked her as a friend, or at least she thought.

"Barry, you are an amazing person, I am sure she will feel the exact same about you."

"You reckon?" He asked curiously

"Yes." She answered while taking his hand.

Before she knew what was happening Barry pressed his lips against hers. At first she was confused but quickly melted into his arms.

"Barry..." she said as they pulled back. "I thought you..."

Before she could finish her sentence Barry interrupted. " I love you, Caitlin Snow."

"I love you too, Barry Allen." Her eyes starting to tear up.

They spent the rest of the evening playing the piano and stealing the occasional kiss.

The next morning Cisco entered the cortex looking for his friends. Suddenly he heard it, 'heart and soul' they had been playing it more then anything else the night before. He quickly grabbed his vibe gear and headed for the music, not sure what he would find, still thinking about the incident with music meister a few years ago and wasn't to keen on letting that happen again.

As he entered the room he saw them. Both sitting at the piano, smiling and laughing. "Since when do we have a music room?" He asked as both of them turned around.

"Forever apparently. I found it a few weeks ago. Courtesy of Eobard Thawne" Barry stated.

"And you never told me? Rude." He acted a bit offended but they both knew he was just joking around like usual.

"Wait. Are you guys?" He looked at the pair with a confused look, not wanting to be too direct in case he thought wrong but they both knew what he meant.

Caitlin pecked Barry's lips. "What do you think?" She turned back to the engineer.

Covering he eyes still. "A simple 'yes' would have sufficed." He yelled. "Though I knew this was going to happen someday." He winked before slowly walking out of the room giving the both of them some privacy.

"He took that surprisingly well." Barry said pulling Caitlin closer.

"Yeah" she said in a soft voice putting her head into his chest.

"I love you, Cait."

"I love you too."

I hope you enjoyed this little quick story. This is my first fanfic so i hope it wasn't too bad. (Please don't kill me XD)
I have a few ideas for a second chapter (Maybe even a third) that will probably be longer too
and if you have any ideas for things i can add/write about feel free to let me know. :-)