I blame the cold. If it was warmer, then maybe I would concentrate more. I asked Spike to fetch me a hot mug of coffee an hour or two ago. Just where did he go with that, anyways?

I yawn. The numbers and symbols blur together in front of me. That's not a good thing. I blink wearily, gazing across the dusty chalkboard, trying to figure out where the numbers begin and where they end.

At this rate, I'll never get anything done.

I start pacing across the library's study, my wings coiled tightly by my side. I don't think I'll ever get used to them. The golden crown is a different story. At least I can set that thing aside when I don't feel like wearing it. It always weighs so heavily on my head. Sometimes I wish I could just take my skull clean off. Mornings like this: I can't sleep well. Too much to process. Too much to think and do.

It's almost a relief when I hear her hoofsteps trotting up the stairs.

“Rarity!” I smile, my heart lifting at the sound of her gasping breath. Did I startle her? “Welcome back!”

“You... you knew it was m-me?” she stammers. I sense her shadow shifting in the dawnlight haze through the windows. “Oh, b-but of course you would... erm... know who it was immediately.”

“What took you so long?”

“Hmmm?”

“You were gone a long time.”

“Oh, well...” She trots closer. I take a deep breath, but I don't smell anything. She's not wearing perfume. How odd. “A lady has to... uhm... powder her nose every now and then, I do suppose...”

I can't help but giggle. Rarity's so cute when she tries to cover up for herself. It's not a crime if she forgot to freshen up before visiting me for once. I'm just glad to hear her, even if I can't take my eyes off this blasted equation.

“What are you working on, Twilight?” she asks in a raspy voice.

“Unnngh...” I feel another cold chill. I rub one forelimb against another, careful not to dust myself with the chalk held in the crook of my hoof. “It's the Clever Hypothesis Equation. You ever heard of it?”

“Well, as a matter of fact...” She stops in mid-speech, then clears her throat. “Actually, come to think of it, my mathematical knowledge took a backseat to fashion and art when I went to school—”

“I don't blame you for being in the dark,” I say. “The Equation was never solved.” I giggle. “That's why it's remained a hypothesis.”

“I see...” I feel her trotting up to my side. “So, is that what you do with your time, then? Work on math problems?”

“Yes, well...” I rub a hoof across my temple. I don't want to tell her just how sleepy I am; I don't want to be rude. “I guess it's a nice distraction from having to deal with my new responsibilities.”

“What new responsibilities?”

“Well, I sort of became a Princess overnight, Rarity. In case you forgot.” I let loose a nervous chuckle and shudder. Good heavens, it's so cold in here. “It helps to have a clear head for dealing with all my new royal duties. Only... I wish I could clear my head. I figured doing some old math computations would help, but... ungh...”

“Twilight, I... I-I don't have much time...”

“But you just got here!” I smile as I receive a burst of inspiration. I levitate my chalk piece forward and add a few figures across the board. The equation only becomes more jumbled, and I groan in frustration. “Ughh... I guess it would be kind of selfish of me to ask for some help with this, especially since it's not really the sort of stuff that you're into...”

“Twilight, darling, be a dear and look at me for a moment...”

“As soon as I figure this mess out, I'll help you with sorting fashion catalogues or calculating the Boutique's budget!” I blurt. “I promise!”

I feel a gentle, velvety-soft hoof under my chin. Slowly, my head turns until I'm forced to look Rarity in the face.

She's smiling, although it is a very delicate, very fragile expression. I see a gloss to her blue eyes, reflecting the white numbers on the other side of me, like dancing stars. “You are so very beautiful, Twilight. I want you to know that... now and forever.”

I blink, my brow furrowing. Eventually, I smile back. “Well, of course, Rarity, because you're always around to make me feel beautiful.”

She cracks an even wider smile, but it looks painful, like a sharp diamond is jutting into her face. She caresses my chin one last time, swallows, and eventually says, “And I always will be around, Twilight. I will never stop thinking of you, ever.” She leans in and hugs me, a very tender embrace.

For a moment, it's not so cold.

“I... uh... I'm glad to hear that, Rarity.” I pat her shoulders as we part. “But I have things to do. If I don't get this equation finished, then I'll never get any rest. Believe me.”

“Do yourself a favor, Twilight,” Rarity says in a hollow voice. “And myself as well.” She shudders as her voice retreats into the shadows of the library. “As soon as you feel like resting, please, do not hesitate.”

“Yes, just one second.” I lean forward, and sudden notion ricochets through my aching head. I erase a swath of figures and replace them with a moderately complex algorithm. I then examine its placement within the grand equation as a whole, and yet another frustrated growl escapes my lips. “How am I ever going to sleep if I just leave this unfinished?! By the time I wake up, I won't even know where I left off!”

“Just what are you working on, exactly?” Cadance's voice asks.

I turn around and squint across the sunny courtyard. “Oh, hi, Cadance! Sorry, I-I really can't do the 'Sunshine, Sunshine' dance right now.” I pivot back towards the chalkboard with a scowl. “This equation is totally kicking my flank.” I gasp, covering my mouth as I feel a flushed sensation through my cheeks. “Oops! Uhhh... are princesses allowed to say the word 'flank'?”

Cadance giggles. It is a gentle wave of laughter, subtle and reserved. She trots over from the Canterlot rose garden and stands besides me, her mane shimmering in the afternoon glow. “Still, you didn't answer my question. What's gotten you so busy, Twilight?”

“Oh, it's just the Clever Hypothesis Equation,” I say in a droning tone. “I'm surprised you don't know about it. It's only the most mysterious, unsolved mathematical quandary in Equestrian history.”

“Oh, I know about it,” she says. She stands closer to me and rests a hoof lovingly on my shoulder. I can't help but smile. “I could have sworn it went by a different name,” she adds.

“Heh... if only...” I shrug the chills off and allow myself to lean into Cadance. I feel happy just having her here. Nevertheless, I gaze despondently at the blurry array of numbers and say, “Actually, it was once named after Starswirl, since it was the famed sorcerer who first postulated the hypothesis. Only, well, it never got solved.”

“Not a very clever math problem...” She looks at me with a wag of her eyebrows. “...now is it?”

We both laugh. A frigid breeze hits us, but it doesn't bother me at the moment. After catching my breath, I say, “Actually, because Starswirl's apprentice Clover the Clever took the task on, historians decided to call the unfinished spell the 'Clever Hypothesis.'”

“It was a joke, Twilight,” Cadance says, nuzzling me. “I always told you that you needed to lighten up and learn to relax.”

I smile and look up at her. “And I will. I promise. But—”

“—you have to finish that equation.”

“Yes. It's just...” I sigh. “It's all I can think about! I won't be able to sleep until it's done.”

Cadance slowly nods. After a breath, she says, “Well, if it makes you feel any better, Twilight, then by all means... tackle it all you like. Just don't wear yourself out.”

“I won't. I promise.” I can't help but chuckle. “Wow, Cadance. Even after all of these years, you're still acting like my personal foalsitter.”

“Do you have a problem with that?” She smirks. “Hmmm?”

“Well, no.” I sigh, smiling. “I just figured that you would have gotten tired of it once you grew up and began running a kingdom.”

“I'll never get tired of looking after you, Twilight.” She brushes her hoof through my mane. It's such a sisterly gesture that I can't even begin to protest. “I... I almost wish that...” All of the sudden, her voice wavers, and I see a shudder to her shoulders. Is she cold too? “I wish that I had spent more time with you, Twilight.”

“Uhhh... you mean like foalsitting?”

“Doing anything.”

“But you had princess duties to attend to—”

“Nothing...” Her eyes are firm. “Nothing can replace the moments I had with you. Please, understand that.”

I stare at her, slowly nodding with my mouth agape. “But... b-but of course, Cadance. I know you always cared for me.” I smile. “The feeling's mutual.”

“I know, Twilight,” she says.

I turn towards the chalkboard as a shadow passes over us. “Then why'd you stop on by? Just to say that?”

Silence.

I sketch a few more numbers across the blackness. “Cadance?” I turn towards my right.

She's not there. All I see are waves and waves crashing upon the beach.

I blink. Curious, I turn to my left. “Shining, do you know what's gotten into Cadance?”

He stands in the surf, staring at me. Gawking at me. A frigid ocean breeze blows through his blue bangs as the water laps up to his well-toned fetlocks.

An awkward smirk crosses my face. “Hello? Equestria to B.B.B.F.F.?” I stifle a giggle. “Cat got your tongue?” I involuntarily shiver. “Jeez, it's cold outside! So much for fun in the sun, huh?”

He stumbles forward—hesitantly at first—then stops a few feet in front of me. He stretches a hoof out, but lingers, as if uncertain whether or not he's allowed to touch one of my forelimbs.

“Twili... you... you can see me?”

“Uhhh... Yes?” I shrug. “Is there a reason why I shouldn't?” I turn towards the chalkboard as a wave splashes against its wooden foundation in the dim evening sunset. “Though, I really gotta work these numbers out or else I'll never get any shuteye—”

I'm practically tackled from behind. A gasp escapes my lips as I almost stumble into the blurry chalk figures. I turn to look over my shoulder. “Shining?! What gives?! Did you dip into the guard bunk's cider store again?”

“Oh Twili...” He holds me in a bear-hug. He nuzzles me deeply from behind, and I hear a sniffling sound in between his words. “I'm so sorry. I'm so sorry that I waited for so long to see you. I was... I-I was just afraid. I was afraid of what I'd see or hear, but it's you! It's really you...”

“Of course it's me! Who else would it be?” I turn around in his embrace and lift his muzzle. A pair of teary blue eyes reflect the ocean's dancing horizon behind me as I wipe his cheeks dry. “I promise that I'm not a changeling. See?” I take his hoof in my own and press it to my heart so that he can feel the pulse. “I'm real. I'm your sister and I love you, big bro.” I wink. “Now, at ease, soldier. You're embarrassing yourself.”

He blinks at me. He chuckles, then chuckles again, raising a hoof to dry his cheek, only to find that I had done so already. The two of us stand like statues in the crashing surf, and he has to raise his voice for me to hear him.

“I... I have so much that I want to tell you, but I know that... uh... that there isn't much time before... before... well...”

“I really don't see what you're so worked up about.” I turn once more towards the chalkboard and grumble, “I'll put this math problem aside, I swear, as soon as I get some headway.”

“It's... uhm... the Clover Theory, isn't it?” he asks.

I almost spit my tongue out. “‘Theory?’ Please!” I gawk at him and chuckle. “See, this is why you should stick to spears and shields, Shining.” I turn to point at the chalkboard. “The Clover Hypothesis Equation was never proven. Sure, Starswirl gave Clover the Clever all of his written dissertations and spellbooks. Heck, he even gave her his skull and horn so she could accomplish what he couldn't. But no matter how many times she calculated and experimented, she just couldn't produce a repeating pattern. So, like any self-respecting magician, she hung the problem out to dry before it could define her entire legacy.”

“Twilight, there...” Shining shakes his head, sighing. “There has to be more than this. I mean, there has to be...” He leans forward with a sad expression. “Is this really all you do? Don't you ever... I mean... don't you ever experience happiness?”

“Well, of course I do, Shining!” I smile back at him. “You're here, after all.”

He blinks, then smiles. It's a strangely bitter thing, but his next breath is sharp and sweet. “Yeah. Yeah, okay.” He gulps. “And I'll come visit you again and again, to make sure you stay that way. I promise.”

“You don't have to promise, Shining.” I nuzzle him, then turn towards the blackness, sketching more white lines against the frigid expanse. “I know you'll be there for me when you need me.” My nostrils flare as I weather another chilling wind. “Seriously, though. Where is Spike with that mug of coffee?”

“Spike sends his regards, Twilight,” her gentle, gentle voice says, instantly warming my heart. “As much as he wants to see you, he can't be here. But he thinks about you night and day.”

“Princess Celestia!” I gasp, dropping the chalk entirely to the plush carpet as I cavort across the royal chambers. I nuzzle her, and she instantly leans her graceful neck down to embrace me. “You came just in time! Maybe you can help me with this math problem!”

“Let me guess...” She leans back, smiling placidly—knowingly—into my face. “The Clover Hypothesis Equation.”

“You know about it?!” I wince, then bop my own head with a hoof. “Well, of course you know about it. It's only the most puzzling, unfinished idea in the history of the magical arts!”

“For good reason, Twilight,” she says, standing perfectly still and watching as I trot back to the chalkboard. “It consumed the life of Starswirl in his latter days, and it nearly claimed Clover the Clever's sanity.”

“Which brings up a good question...” I mutter aloud as I try adding a few numbers into a key spot, only to fail again. “Mmmf... Since you've been around for so long, Your Majesty, why didn't you bother taking up the equation yourself? Huh?” I smile in spite of my frustration as I scribble and scribble. “I'm certain you would have solved it in an instant!”

Celestia slowly shakes her majestic head. “I felt it was best to leave the spell to a pony better equipped than I to not only finish it, but to make use of its properties.”

“Well, that's an awful shame, if you don't mind my saying so, Princess!” I sigh and lean back from the blurry figures. “Because the possibilities of this experiment are mind-blowing! Literally!” I giggle and mutter in awe. “To imagine... if there was actually a way to prove that Starswirl was right about stabilized mana-particles...”

“His ideas on the topic were quite radical, if I recall...”

“But they still had the potential to be tested fully, if only somepony got the mathematical application of mana-particles right!” I exclaim. “Through a well-preserved stasis field, mana-particles could hypothetically mimic a unicorn's very own memories within the fabric of their horn. Starswirl postulated that a unicorn's horn could then be used as a vessel to carry their thoughts for an indefinite period of time—so that other unicorns and alicorns could join with those thoughts through use of a basic synchronization spell! If the field was stable enough, a unicorn's memories could be tapped into for months... years... even ages after the spell was first cast!” I turn and grin at Celestia. “Could you imagine being able to talk to Starswirl again? So many centuries after his death?”

Celestia very calmly nods. “Yes, Twilight. I can.”

“Then how come you never jumped on this sooner?” I turn towards the chalkboard with a frustrated growl. “It's all I can think about!”

“Twilight...”

“And it's driving me crazy!”

“My good and faithful student...” Her hoof is like soft silk against my shoulder. I turn towards her without her having to urge me. A loving expression takes up all that I can see. “I think that it's time that you put the equation to rest.”

“But... but...” I bite my lip. “Don't you trust my talents, Your Highness? If I just work on this a little bit harder, I'll be able to solve it! I just know I can! The impact it could have on the sciences is indescribable...”

“Twilight...” Celestia's horn glows as she gently but forcefully removes the chalk from my grasp. She places a hoof on each shoulder this time. The darkness bends away from her radiant smile. “Let it be. Relax... and be at peace. I have every faith that you can and will solve the problem someday. Right now, though, you could use some sleep.”

I blink. I can no longer see the chalkboard; I don't even care. A yawn escapes my throat, and my eyelids hang with sudden heaviness. “Mmmm... Yes, Princess. You're right.” I sigh as I nuzzle one of her hooves dearly. “You're always right...”

She doesn't say anything. She picks me up in a magic field and floats me towards the bed in the far end of the ornate room. It's already prepared, and the duvet is warm to the touch. It's hard to keep my eyes open.

“It's... it's been really cold today...” I mutter in between habitual yawns. Darkness falls beyond the windows as she tucks me in. I start sinking into the royal pillows. Sinking, and sinking some more. “All this morning... this afternoon...” I shiver slightly, my teeth chattering. “I sent Spike out for some hot coffee. Don't know where he is...”

“Shhhhh...” I feel the bed shifting. A sweet hoof caresses my cheek, like satin through a sea of clouds, blurry and nebulous and lulling me into shadows beyond shadows. “Just rest for a while, Twilight. Don't worry about anything. It's alright if you want to sleep.”

“Sleep...”

My heart jumps and my eyes flash open.

“Sl-sleep?”

I look up and gasp.

“Princess Celestia!”

What's she doing here?! Where am I?

“D-did I miss my alarm?!” I hiss and try to kick the covers off. “Oh no! Morning lessons! I... I-I'll study for the quiz! I promise!”

But she urges me to lie back down in the center of some large bed. “All of your studies are done, my student. You are not tardy for anything, I assure you.” Her pale features are as smooth as porcelain, like a full moon. Is it night outside the palace? I’m in the palace, right? Good grief, it's so cold.

“So... so cold...” I curl up under the covers that she's stretching over me. “Don't... d-don't know where...” I clench my teeth. “I'm afraid...”

“Of what, my student?”

I shiver, my eyes darting about the shadows and shadows. “I don't know.” Gulping, I glance up at her. “Would you... st-stay with me, Princess?”

She smiles. She lies down and curls around me, stretching a wing over my figure. It's warmer than any blanket ever. I smile and lean into her.

“Just like old t-times?” I murmur in a foalish voice.

“Indeed...”

“Princess?”

“Yes, Twilight?”

“Will... will you be here wh-when I wake up? So long as y-you're not mad at me for sl-sleeping in?”

She leans in. She nuzzles me and whispers, “I'll be here for as long as you need me, my apprentice.”

“Hmmm... That's nice...”

I curl up against her white coat and close my eyes. Everything is calm, warm, simple. A clean slate.

“Nice...”

Author's Notes:

http://www.youtube.com/watch?v=Pu_-zizFYbc

Wrote this fic 'cuz I couldn't sleep.