Twilight made her way through the woods of Equestria, navigating the thick foliage as carefully as possible. Who knew what creatures lurked within...what was the forest called again? The Everfree Forest, yes that was it. She may now know much about Equestria but the tales of all the animals lurking in forests, some of which were merely waiting for ponies like her and other unlucky creatures to stumble into their traps. She did know that there was a castle here, or at least the ruins of one, in the forest's center. It was probably filled with all sorts of artifacts, old tomes just waiting to be read...err, and the maybe even Lady Rarity, of course. The other forests and towns in the area had no places where the young mage could detect Rarity with the tracking spell she had cast, which gradually narrowed down the territory she had to cover.
Then there was also the matter of how to handle whoever it was that took Rarity. It was not a wild dragon or some kind of brutish creature that ran off with the Lady Rarity, whoever did this was sneaky and must have planned something in advance.
...
The castle was bigger than Twilight expected, and she decided to teleport to the gate instead of risking discovery if she were to use the shaky rope bridge outside. Her hands shaking, she pushed open the large door that had managed to withstand the wear of time to enter, her horn glowing brighter as she neared wherever the Lady Rarity was being kept.
She hadn't gone far when she caught the shadow of another pony, who most definitely was not Lady Rarity. Twilight wished she could've snuck up behind this pony and then faced them but she tripped on the edge of her mantle as she attempted to crouch and sneak along at the same time which ended up with her falling forward and landing right in front of this stranger. She could see that they were a unicorn mare with a pink coat and a mane of purple streaked with green. She wore a magenta suit and clutched a staff which Twilight honestly thought resembled a two prong fork but she wasn't going to say that in front of her.
"Well, what do we have here?" She said sticking on of the prongs of her silly fork staff under Twilight's chin.
"I-I have come for the Lady Rarity," Twilight stuttered.
Even though Twilight saw her eyes go wide this mare didn't loose her cool, "Well that's going to be a bit of a problem."
Twilight gulped as the malicious stranger's horn and staff glowed with energy. How'd she get herself into this?
...
Starlight Glimmer, that was the name of this mare who had abducted the Lady Rarity and was now fighting her in a hall, shouting accusations and curses to the mage. Twilight's horn was lit with her own magenta magic. Most of this duel had been her attempting anything to mimic anything remotely similar to her brother's shield spell against all the vicious blasts Starlight conjured up. Between these attacks Twilight had pieced together Starlight's story from the things she shouted at the purple unicorn.
"You did all this just because you have no friends?" Twilight called incredulously.
Starlight gave a curt nod and a cruel smirk before firing another blast from that silly fork staff. Twilight promptly deflected this by using her magic to encase her hand in aura so she could smack the spell away safely.
"I haven't got any friends either, Starlight. This doesn't mean I'll selfishly hurt others like you have so others might be deprived of their friends and family."
Starlight didn't falter but Twilight had a surge of confidence and charged Starlight, horn glowing with a sleep spell that was sure to put the other mare out for a few hours. The pink unicorn noticed what Twilight was doing and evaded her movements.
Somewhat frustrated with Starlight's unoriginal spells, Twilight let the spell on her horn die until Starlight Glimmer prepared another blast with her staff. The pink unicorn wasn't as calm as she had once been, her eyes flashed with anger and her hands gripped her staff tighter.
Starlight's greenish aura met the magenta of Twilight's latest spell and the two colors collided. With much effort Twilight's aura pushed back Starlight's until the other mare let out yelp as Twilight's magic overwhelmed her.
...
A few twists and turns in the old stone hallways later, Twilight Sparkle found herself being smothered by some kind of creature made out of fluffy clouds...and sequins?
Well, there was a bit more to it than that. Twilight had found the Lady Rarity wearing a strange necklace and staring blankly at a wall. When Twilight lifted the necklace over the white unicorn's head she was careful not get her purple curls tangled. After that she saw her eyes clear. Ponies said that the Lady Rarity had eyes like the clearest of diamonds. Twilight thought that was the stupidest thing she had ever heard, first she thought they could have at least specified that the diamonds in question were blue, and secondly how could somepony compare diamonds to Rarity's eyes? One was the shining beacon of beauty and the other...well it was really just a rock, now wasn't it?
All this brought Twilight to where she was now. It took her a moment but she figured out that heavenly entity was not a cloud, but the Lady Rarity. Oh, and she was also having a bit of a hard time breathing through the tackle-hug and the glitter dress.
By the time Rarity let go Twilight was at least three shades of purple deeper and sputtering for air. Meanwhile, Rarity was brushing a bit of dust off her skirt before she looked back at Twilight.
"Oh, it's you! You're my rescuer!"
"Well-"
"You're Twilight Sparkle, the captain's dorky little sister!"
"Umm...?"
"Don't worry, darling, being dorky is hardly a crime."
"I see..."
"I've heard that you are a scholar whose knowledge rivals the library itself. What do you have to say on the matter?"
"Err...umm...you see...uhhh...well...hi?"
Rarity laughs, "You may be a scholar but your social skills could use some polish, hmm?"
"I-"
Rarity takes Twilight's hand and removes the necklace from her grip. She holds it away from her face with a look of disgust on her face. "What are we going to do with this?"
Twilight reached out to cup the charm in her hands. "Do you know any good spells?"
Rarity's brow furrowed, "Good how, Twilight Sparkle?"
"Umm, it's just Twilight and 'good' as in...well happy, kind, love, and laughter. Do you know any light magic?"
Rarity nods and lights her horn with blue aura. Twilight's magenta reappeared and they began to pour all their magic into the heart. Every moment of happiness each had ever felt, each smile they had seen and every one that they had returned.
First, the chain snapped.
Rarity and Twilight continued, this time adding the love of their family, their crafts. Every time Rarity loving sewed a new design together and made something unique while Sweetie Belle simply spilled glitter more often than not and Twilight added memories of reading books alone by candlelight and playing with Shining Armor and Cadance as a filly.
Next, the heart grew.
Soon after pouring in their love of the Crystal Empire they each decided to add something more. Rarity added Twilight's awkwardness and humble bravery which had certainly been noted by the white mare. Twilight shifted slightly and hoped Rarity wasn't going to find out about how she thought each curl of her mane was perfect or that her eyes were prettier than diamonds or how her joyous laughter proved she had a heart to match.
When both mares looked down to see if their magic had dispelled whatever evil curse was on the necklace they found a shining crystal heart balanced on their palms. Twilight and Rarity gasped in unison.
"What is this, Twilight?"
"I-I'm not sure," answered the purple mare, "Well, not one-hundred percent sure what it is but I think we should take this back to the Crystal Empire with us."
Twilight Sparkle left the ruins of the Everfree forest with the crystal heart tucked under one arm and Rarity's hand clasped in the other. Starlight Glimmer would wake up in an empty castle a few hours later with a lot to think about and a second failure to her name. By that time Rarity and Twilight would be home in the Crystal Empire showing off their latest treasure to Princess Cadance and Shining Armor. That treasure would come to be known as the Crystal Heart and was enchanted with the love of every one of Cadance's subjects, but most of all, Rarity and Twilight's. Cadance and Shining Armor would get married in front of the heart, which had replaced the taxing shield spell both used to control. Years later Rarity and Twilight would stand in front of the heart for the same reason.