The 'Mesolimbic Dopamine System', made up of the Ventral Tegmental Area and the Nucleus Accumbens, is an integral part of the nervous system. It is responsible for the rewarding of the brain whenever a pony performs a task with an evolutionary benefit, such as eating, or engaging in coitus.

Recently, however, the 984 study from the Canterlot Journal of Neurophysiology has shown that whenever a 'love-struck' pony was shown a picture of their partner, there was activation in that very same area of the brain. This provides evidence towards the theory that love is not just a preferable pastime to ponies, but is also an integral part of ponykind's evolution and survival.

See Figure 12 and Figure 13 for the relevant FMRI scans.

"Urghh..." Twilight Sparkle groaned, as she slowly shut 'The Science of Love' with a muffled thud.

She yawned a long, quiet yawn at the unhelpful book. As she did, she proceeded to stretch her legs straight out on the bed, her lavender eyes scrunching shut for a few moments, before she began tucking her hooves back underneath herself.

Pulling the bed sheets tighter around herself with her magic, she buried her muzzle into the star-adorned blanket. She huffed tiredly into it, and flicked her tail in frustration. As fun or interesting as reading about the scientific aspects of love was, she was still no closer to figuring out how exactly she felt about Rainbow Dash.

This wasn't a complete surprise, of course. This had been the seventh book now that had outright refused to sum up her own feelings into one clean paragraph. And after many a sleepless night like this one, the lavender princess had already begun to lose hope on ever figuring it out for herself.

"Gah!" Twilight complained, lifting the tip of her muzzle into the air. "Why does this have to be so difficult? All I want is a way to sum up several years worth of complex thoughts and feelings into one succinct statement. Is that too much to ask for?"

She paused, blinking.

"Maybe it is," she admitted quietly. She took a deep breath, and flopped her head back down, her wings splaying out either side of her.

She lay there for a while; her mind carefully going through and picking out all of the somewhat-helpful information that she had gathered over the space of this afternoon, before quickly and discreetly stuffing it all into a mental compartment labeled 'Read It Later'. As she did, her memory came upon one of the very first books she had read on the subject at hoof.

'Love is the most socially acceptable form of insanity.', the first line of the book had read. This was, of course, followed by a good twenty or so chapters of humorously pretentious quibbling, of which that first line had only previously alluded to.

Twilight giggled. It had been a good read, she had to remind herself. The particular style of writing had always kept a smile on her face, from chapter one all the way to chapter twenty. Well, as soon as you got past all of the overemphasis on the fact that love was some sort of saliva-transmitted infection, and that the entire world was doomed to be taken by love and harmony.

There was a bright flash of light, quickly followed by the loud crash of thunder.

Twilight started, jumping a little in place. Startled by the sudden interruption to her thoughts, she furrowed her brow at the storm brewing outside. Her eyes tilted up to see that the bedroom window now had streaks running, like stretch marks, down it's surface.

"Urghh..." She groaned again.

Twilight didn't enjoy the rain, despite the overwhelming general consensus that it was somehow peaceful. She had never really understood that particular train of thought, nor did she ever plan to, either. Rain was noisy, wet, and irritating, even at the best of times. It was only when she was with her friends that the rain became somewhat manageable.

They could at least distract her from the fact that there was probably a book out there, somewhere, getting absolutely soaked and ruined beyond repair.

It would have probably been a good book, too. Like '15 Fun Things To Do When Time Stops', or 'A Hitchhiker Pony's Guide to the Galaxy'.

The very thought of it just unnerved her.

Knock Knock Knock

Curious, Twilight cocked an eyebrow toward the bedroom door.

"Hello?" She called quietly. "Spike?"

There was a brief silence, before a shaky voice could be heard calling back.

"T-Twilight? Are you still awake?" Spike asked, pushing the door open with a creak. "There's a storm outside, and uh... I was wondering..." His voice trailed off as he silently twiddled his thumbs.

Twilight grinned at the young dragon hovering awkwardly in the doorway. She knew exactly what he was getting at.

Ever since he was just a baby, Spike had always been outright terrified of storms, though his inherent dragon pride had never really let him admit it to anyone but himself. She was thankful, though, that he was at least mature enough to request his big sister's company during the fact.

She would never, ever want him to just suffer in silence, just because he thought that he was 'too grown up' to admit that something scared him. Everybody was at least scared of something.

The librarian shook away the silly thought, and put on her most thankful smile.

"So you came to check up on me, huh?" She mused, giggling jovially at him. "How chivalrous of you, Spike."

"Wha- Oh! Oh, yeah. Totally." He laughed, rubbing his arm with a claw nervously.

Twilight giggled again. Spike could be so sweet sometimes. "Well, why don't you come and keep me safe?" She asked as she lifted a wing, making the blanket that rested upon it raise and reveal a small cubbyhole of warmth. She tapped the spot invitingly.

Spike looked apprehensive for a few moments. He quickly shrugged that off, however, when the sudden crash of thunder boomed from outside. He hurriedly waddled over to the bed, before climbing up and into the cocoon of warmth.

Twilight grinned at him, as she let her wing fall and cover the small dragon in feathers and duvet. She received a muffled coo of approval in response.

The two then slowly lapsed into a comfortable silence for the next few minutes, listening to the rattling of the window. Every so often, Spike would fidget as he got comfortable, before he finally found his spot and curled in on himself as he did naturally.

Eventually, Spike broke the silence.

"So, 'The Science of Love', huh?"

Twilight cheeks immediately set ablaze. Glancing around, she quickly noticed that the book she had been looking through earlier was sat near to where Spike had made his temporary nest, and was well within his field of view.

"Hmm?" She hummed, feigning ignorance. Her ear twitched. "What do you mean?"

Spike sat up and raised an eyebrow at his half-sister. "The book, Twilight." He explained, pointing a scaly thumb at the tome. "You know, the one about how love is 'an integral part of ponykind's evolution' and all that."

Twilight stared as he made air quotes with his claws. A part of her desperately wanted to ask how he knew the book word-for-word, but she realised that the young drake must have scoured the romance section of the library, much like she was doing now, in order to gain some ground with Rarity.

The librarian noticed that she was still staring, and shook her head. She then frowned as an unruly lock of her mane partially obscured her vision. "Oh, that?" She asked, tucking the lock of mane behind a twitching ear. "I was just doing a spot of light reading. Nothing too important."

Spike exhaled air through his nose, and smirked. "Yeah, sure. Just like how the last seven romance books you checked out of the library log were light reading, right?"

At the mention of the library's book log, Twilight's ears drooped. "Oh. You noticed that?"

"Yeah," he chuckled, nudging Twilight's side jovially. "I have to check that thing daily. You have no idea how many romance books Rarity checks out on a weekly basis. It's almost as much as Applejack."

Twilight sputtered, whipping her head toward the grinning Spike. "A-Applejack? Since when was she interested in that sort of thing?"

"No idea. She just came in a couple days ago, demanding to borrow the entire romance section. Can you believe it? I had to tell her that there's a limit to how many you can borrow, but she was pretty adamant about the whole thing." Spike laughed, wiping a tear from his eye.

"Huh," Twilight intoned. "Who knew?"

Spike shrugged. "I asked her what the deal was, but she just went really quiet and started muttering something about Rarity..." he trailed off.

"Hmm... That is odd," she agreed.

Twilight had to wonder if Applejack was going through the same thing as her. Was that even a possibility? She'd need to remember to ask the next time she saw the farm mare.

"Anyway," Spike suddenly spoke again. "Have you talked to her about it yet?"

The alicorn blushed, her gaze pointed anywhere but at the curious green eyes of her little brother.

"So that's a no, then? Fair enough. It is pretty difficult, isn't it?"

Twilight went quiet for a moment, before sighing heavily. "Yes. Yes it is. Every time I try to talk to her, I just... I dunno, I just can't do it."

Spike hummed his agreement, and snuggled up closer to Twilight.

"Tell me about it, sis." He chuckled. "Every time I try to talk to Rarity about it, I just lock up. I just can't get a word out, even though there's tons of things that I want to say to her. Like... how her voice is as smooth as silk to my ears."

"Or how her face lights up when she flies..." Twilight trailed off, her eyes going glossy.

"Or how she carries herself so professionally, like a model on a catwalk."

"Or how you could just get lost in those magenta eyes of hers."

The brother and sister let out a pair of dreamy sighs.

The room fell quiet once more.

Spike yawned, a small tuft of green flame curling under the roof of his mouth. He then closed his maw with a snap, causing the dragon breath to extinguish and waft smoke out of his nostrils. Letting his eyelids droop, he sat up slightly and leaned into the crook of Twilight's neck.

"Twi?" He asked sleepily, his eyes closed.

"Hmm?" She responded, anticipating what he was going to ask next.

"Can I sleep in here with you tonight?"

Twilight smiled at him, and pulled her wing tighter around the sleepy dragon. "Of course you can, Spike. You need only ask."

Spike hummed appreciatively, and quickly drifted off to sleep. Twilight waited patiently for Spike's snoring to begin, a telltale sign that the dragon was actually asleep and not just faking it, before carefully and quietly levitating The Science Of Love back up to her. She took a moment to nuzzle Spike, then went back to her reading.

"Just a few more chapters," she whispered to herself. "A few more chapters, then I'll go to sleep. There has to be something in here that helps me in some way..."

It was long into the night when Twilight eventually let her eyes close long enough for sleep to claim her.

Author's Note

Oh, wow! It's a pre-sequel! How ~~copyrighted~~ odd is that?

Also, my head-cannon is that Spike uncontrollably does the air-quotes thing with his claws whenever a pony quotes something, despite how far away from the pony he actually is. Just because he's the only one in Ponyville with posable digits.

It makes me giggle.