A/N: this idea came to me earlier, and while I should be writing my chapter stories, I couldn't forget it - so here you go!

Two boys lay on their backs beside each other, staring up at the sky.

"You know, Theta, you need a hobby." One spoke to the other. Theta turned to face his friend.

"I have hobbies." He said defensively. His friend chuckled.

"Name one, Thete. Just one." He replied. Theta frowned in thought and remained silent, causing his friend to begin laughing once more. "Don't worry, though. I'm going to help you find one. Otherwise you'll go mad."

Theta huffed and looked back to the sky. "If you must, Koschei." He sighed.

dwdwdw

Koschei and Theta sat across from each other on the floor of a large room. Beside them was a large instrument that Theta was largely unfamiliar with.

"Be prepared to be amazed!" Koschei grinned, standing to move closer to the instrument.

"Kos, why are we here?" Theta complained. His friend shushed him.

"You wanted a hobby, I'm giving you one! Or, I'm sharing mine, actually." Koschei explained. He gestured to the black and white keys of the instrument. "This is a piano, Thete. You play the keys, and it-"

"I know what it does, Koschei." Theta interrupted, embarrassed to have Koschei patronise him. Koschei held his hands up in defence, before leaning in to begin playing.

"Listen." He whispered. Theta rolled his eyes and nodded.

Koschei began to play a simple childish tune they were both familiar with. He stumbled on several notes, but the song was recognisable all the same. Once he finished, he smiled and raised an eyebrow as if to say "Well?"

"It's alright." Theta replied. Koschei frowned.

"Won't you at least try? I'll help you." He whined. Theta shrugged and joined him at the piano.

The song sounded clunky and broken as Theta played one hand and Koschei played the other, considering neither were particularly experienced in playing. Koschei spoke instructions to Theta telepathically as they played, slightly improving the sound.

As they finished, Koschei turned to Theta once more.

"If you're not interested, then suit yourself. I can always teach you more if you did like it, though." He suggested. Theta smiled.

"Maybe one day."

dwdwdw

Living in the vault for a prolonged period of time was never going to be a fun activity for Missy - although, she supposed, it was a step up from execution.

It did rather help her improve her piano playing, however, as practicing piano seemed to be the only thing to do. It was calming for her, and felt as if it was the only thing that could make her feel as if she was simply Koschei once more.

The Doctor occasionally visited, however he never listened to her play. Or, more correctly, she didn't allow him to listen. She refused to perform for him, or even be heard by him. It would bring back memories for both timelords that neither needed to relive, which would only bring guilt and sorrow.

Once or twice the cyborg who looked like an egg had listened, either during guard duty or the occasional vault visit where he had accompanied the Doctor. He had even tried to compliment her playing, however she had brushed him off with death threats and insults. The last thing she needed was a walking egg trying to befriend her.

Playing music was a solitary activity for Missy to undertake, one of the few things that kept her from complete and utter insanity. She didn't feel as if she was ready to share that.

dwdwdw

The Doctor had spent the majority of his day repairing small faults in the TARDIS and ridding a department store of a minor alien invasion. However, after all of that was complete, he found himself at a loss for things to do, therefore he decided to visit Missy.

He flew the TARDIS to land outside the vault as to avoid any long trips, and stepped up to the vault door. That was when he first heard it. A faint echo of classical music vibrating through the huge vault doors. He questioned whether Missy had somehow smuggled in a music device - or worse, kidnapped a musician.

The doors swung open, however Missy didn't move for several seconds, continuing to play the piece she had been playing. The Doctor froze in shock as he realised it had been her playing.

"Missy." He breathed, shocked as childhood memories resurfaced and left his hearts aching. Missy's head snapped up and she turned to face him all in one rapid movement, slamming the lid on the piano down.

"Doctor." She replied. Her eyes showed an emotion generally unfamiliar in Missy, a sudden vulnerability.

The Doctor approached the piano, and placed a hand on it gently. "I didn't know you still played." He muttered.

"I don't." Missy snapped. She stood up from the piano quickly.

"You just did." The Doctor pointed out. Missy shook her head, but gave no further reply. "It was beautiful. You've really improved." The Doctor admitted.

Missy chuckled softly. "Anything was an improvement from the last time you heard me play, Thete." She replied. Her eyes grew wide as she noticed her mistake, and the Doctor realised that she too must have been reliving old memories.

"You haven't called me that in a long time." He smiled slightly. Missy frowned angrily - whom the anger was directed at, the Doctor wasn't sure.

"Leave." She growled. The Doctor sighed.

"You don't always need to run from dealing with things like emotions, you know." He spoke. Missy shook her head sharply and looked away. The Doctor stepped closer, and gestured to the piano. "You know, you once promised me a piano lesson or two."

"I think you'll find I never suggested two." Missy said quietly. The Doctor chuckled.

"You didn't specify otherwise." He replied.

Missy shrugged, and hesitated visibly before pointing to the piano seat. "Annoy me, and I'll kill you." She whispered.

The Doctor sat beside her, and smiled at the emptiness he could see in her threat, a skill he had developed over time with Missy. He felt Missy's voice enter his head, and their minds combining to create one shared mind.

You play right hand and I'll play left. She commanded telepathically. The Doctor nodded and placed his hand on the keys. Just before they began to play, he looked to Missy. Strangely, she had already been looking at him, and they shared a glance before turning back to the piano.

I'll always be better though. I hope you know that. You need a different hobby, I don't think this one is for you. She smirked. The Doctor rolled his eyes.

The never ending debate. I have a hobby! I play the guitar. He replied. Missy chuckled aloud.

Just shut up and play. She replied. They both turned their attentions back to the piano, and realised the sound they had been creating.

Gone were the clunky, broken tunes of childhood, replaced by a beautiful cooperative melody with the occasional missed note on the Doctor's part.

"You're not bad, Kos." He said quietly aloud. To his surprise, Missy didn't snap at him or demand he leave for the use of her old name.

"You're... you're still bad, Theta." She smirked.

The Doctor chuckled.

"Sure, Kos."