A/N: I wrote this randomly one night in a PM to AllHandsLinked, whom I thought could include it in her Doctor Who/Glee crossover stories. But what started as a quick outline of my idea turned into what could be considered a oneshot. Anyway, I got the idea for this when my astronomy teacher mentioned something called "radio galaxies" which are galaxies made up of radio waves. He said, and I quote "They can't be seen, but they can be heard." And thus, this little idea popped into my head and I couldn't resist.

For those who don't know, Eutrepe is the Greek Muse of Music.

Disclaimer: I own neither Doctor Who nor Glee, for if I did I would be living in a TARDIS that had a slow-motion hallway.

"Kurt, could you open the door for me?"

Kurt frowned at the Doctor who was lounging on his swively chair, one foot moving a lever up and down while he fiddled with his tie.

"But we haven't landed yet."

The Doctor didn't seem to hear him - that, or he was just ignoring him. With a sigh, Kurt went over to the Tardis doors and yanked one open. Unsurprising, he found himself staring into empty space, a few distant stars twinkling at him.

"Tell, me Kurt, what's out there?"

Kurt glanced back at the Doctor, who had not even looked at Kurt.

"Nothing. Just a few stars."

The Doctor chuckled and glanced at him, smile twinkling in his eyes.

"Think again, Hummel."

Kurt frowned and looked out the doors again. "I don't understand. What am I supposed to be seeing?"

"Not seeing. Hearing."

"Huh?"

The Doctor looked at Kurt's bewildered face and after a look of confusion crossed his own face, a light seemed to flick on in his brain as he realized something.

"Oh!" The Doctor jumped from his seat, letting go of the lever. The Tardis began to tilt, but the Doctor grabbed the lever quickly and after a few pushes of buttons, everything was stabilized - well, as far as the Tardis stabilizes, anyway.

"I completely forgot that you can't hear this without a proper source of transmission!"

"Hear what?" Kurt asked, annoyed.

"Of course I would completely forget," the Doctor continued without any indication that he had heard Kurt. He began fiddling with some dials and buttons on the other side of the Tardis console. "After all, I've been hearing them since before I could remember - and let me tell you, that is a long, long, long, long, long, long-"

"Okay, I get it! Now what is it that you hear that I can't?"

"This!" Proudly, the Doctor hit a last button and suddenly the Tardis was filled with music.

It was unlike anything Kurt had every heard before. It was no instrument he could name, but it was music nonetheless. The unknown melody seemed to reach into his heart and tug at his soul with its hauntingly beautiful sounds. At once it would be soft and light, crooning lovingly to him, and the next powerful and loud, threatening to break his heart with the unimaginable emotions toiling behind it. Kurt had never heard anything like this before.

"What is that?" he whispered, eyes closed as he listened to the music.

"That's the Euterpe Galaxy. Made up completely of radio waves. It sounds like it's singing, doesn't it?"

Kurt nodded, feeling tears prickle at the corner of his eyes. "It's beautiful."

Opening his eyes, he turned back to face the open door, and wondered how something so wonderful could come from seemingly nothing at all.

"Isn't it? This isn't the only one, though," the Doctor said as he came to stand next to Kurt in the open doorway. He leaned a hand against the top of the doorframe and looked out with him. "There are billions of radio galaxies out there, each with its own song. This one is my favorite though."

"Why is that?"

The Doctor paused. "There's something about the Euterpe song I can't place my finger on. It's so different from the rest. It's not the most powerful, or the loudest, but it just...I don't know. It's difficult to describe."

"It makes you feel like you're not alone," Kurt whispered as something new came through the song, and he realized that all the emotions he was hearing - they were emotions he had felt at one point in his life. Grief over his mother, love for his father, fear of bullies, pride for his friends, and loneliness - feeling alone in the universe even though there were others out there just like him. Except that he couldn't see them.

But he could hear them.

"Kurt? Are you alright?" The Doctor's voice was soft.

Kurt hastily wiped away the tears that had escaped down his cheeks. "Fine."

The Doctor sighed and pulled out his sonic screwdriver. He pointed it over his shoulder and the music was cut off. A hush filled the Tardis again as neither of them felt the need to speak. The echoes of the song reverberated silently throughout the impossibly large room as the Doctor closed the door and they both made their way back to the console. Kurt sat down on the metal grate, leaning against the railing, knees drawn up and hands pressed against his legs. He watched the Doctor walk silently over to the other side of the console, put on his glasses, and start turning a few dials.

"Is there-?" Kurt began, then stopped. The Doctor looked up at him over his glasses.

"Is there what?"

Kurt licked his lips, before continuing. "Does anything live there?"

The Doctor blinked at him. "In radio waves?"

Kurt nodded.

The Doctor glanced down at his hands, studying them intently as he thought of an answer.

"I honestly don't know, Kurt. I've never actually been inside one to know. Whatever lives in there - if something did, that is - would be made up of radio waves - it would be so much a part of the galaxy that it would be difficult to separate a single sentient being from the rest of the wavelengths. Why do you ask?"

"It's just - I just thought that there had to be something in there with all those emotions. I just find it difficult to believe radio waves can make such music on their own without someone or something to compose them."

The Doctor made his way over and sat down next to Kurt, one leg drawn up and the other stuck out. He looked at Kurt, who looked back at him.

"It's a stupid idea, isn't it?"

The Doctor shook his head. "Actually, I think you might be right."

"You - you do?"

The Doctor nodded. "Except that it might not be a whole bunch of living beings."

Kurt frowned. "What else could it be?"

"Did you ever think that the galaxy itself could be alive?"

"The whole galaxy? But how?"

The Doctor shrugged. "I once came across a living sun, so why not a galaxy? Particularly one made of radio waves, if you think about it. There all just out there, swirling together in one giant mass of sound, invisible except to itself."

"But - all those different emotions? How could just one thing feel all of that?"

The Doctor looked at Kurt in a way that said so much more than he could ever out loud. And suddenly, Kurt knew that the Doctor suffered all of the emotions Kurt had felt when he listened to the galaxy sing. He knew grief and sorrow, love and fear, pride and shame, just as much as Kurt did.

Without a word, Kurt nodded.

He understood.

He understood completely.