The following work was originally written as a response to a claim made on the "1sentence" theme community on LiveJournal, which basically sees you taking a theme set and writing a sentence for each theme based around your pairing of choice. These aren't actually going on the community; I'm writing another pairing from another fandom for my second claim; however, I didn't feel like giving these up. So here they are.
Before I begin, yes, Buttercup and Princess are teenagers here, for reasons of propriety and stuff, yes there is yuri and hints of sexuality, and yes, Slim buggered up some of these prompts. Forgive him; he's an idiot.
#01 - Air
As she and her sisters zipped through the air, ready to connect with the young villainess, the green eyed teen locked eyes with her adversary and wondered why she saw herself reflected in her face.
#02 - Apples
"You're such a pig" Princess sniffed as she watched Buttercup devour the apple, finishing the fruit in two bites, leaving juice on her chin in the process.
#03 - Beginning
Neither Buttercup nor Princess admitted that a new beginning might be at hand; the two still regarded each other as enemies, even when freshly parting from a passionate kiss.
#04 - Bugs
She didn't mean to slap her forehead when the heiress began screaming due to the beetle dropping onto her head, but when one fights bugs fifty times that large, it becomes difficult not to laugh at the concept of fearing something so small.
#05 - Coffee
Princess stirred some creamer into her coffee, took a slow sip, gazed at her plans for the latest heist, and smiled, knowing a certain green-eyed someone was guaranteed to come flying in and play right into her hands.
#06 - Dark
Sometimes, Buttercup wonders if she isn't all good, if there's a dark side of her that's waiting for an opportunity to indulge in all that heroes cannot have, and if that explains the negligee-clad villainess lying in bed next to her.
#07 - Despair
Princess felt herself die a little with every rejection thrown her way, yet after all the years, she still longed dearly to be associated with the Powerpuff Girls, not only for the attention, but for another (green eyed) reason.
#08 - Doors
As she passed through the ornate doors of Morbucks Manor, Buttercup felt as if she was entering another world, a place of gold, narcissism, and greed, where the young woman she loved resided, like a bird in a gilded cage.
#09 - Drink
For Buttercup and Princess, power is something to be relished, drank and enjoyed like a fine wine.
#10 - Duty
Buttercup looked aside as Blossom launched into a familiar diatribe about their duty as crime fighters; with the mentions of the villains that threatened Townsville came a mental picture of Princess, and a reminder of how she could never be true to that "glorious" duty so long as the heiress had her heart.
#11 - Earth
She narrowed her eyes at the redhead, who smirked, knowing that her quip about their not really needing to give a shit about saving the earth had hit a nerve with the green Puff.
#12 - End
Buttercup knew that this love affair was destined to end badly; this clash of personalities, struggle for power, fight between good and evil would never lend itself to a long term relationship, but she was sticking around for the ride anyway.
#13 - Fall
Fall was Buttercup's season: she loved the way it was constantly moving in flux, the piles of dead leaves, the brisk air, but lately it was the orange color the leaves turned that brought a smile to her lips and a strange stirring in her heart.
#14 - Fire
The fires of anger swelled in Buttercup's chest as she realized that Blossom was right, Princess might be using her; her fist tightened as she faced the rich teenager, and she struggled to quench the flames as she looked into her lover's face and forgot the redhead's true nature for the sake of being near her again.
#15 - Flexible
It had taken Princess years to achieve the same flexibility and finesse in fighting that had taken Buttercup moments to attain; then again, years or not, she was there and able to rival the green Puff in that department.
#16 - Flying
The heiress and the heroine soared over Townsville at night, both thoroughly nonplussed by the view and thoroughly content with the ability to be literally above and beyond most of the citizens.
#17 - Food
Princess tastes very sweet for such a bitter girl, Buttercup muses: caramels, chocolates, creme brulee- all are evoked by her flavor.
#18 - Foot
Before Princess could react, Buttercup sent her flying with a kick to the stomach, only for the heiress to retaliate with a laser blast from her glove.
#19 - Grave
It would be so easy to send Princess to an early grave, Buttercup would think on the darker days; she could easily destroy the villainess as she lay next to her in bed...
#20 - Green
Princess bedecks herself in gold, but she's terribly fond of green as well- the color of money and Buttercup.
#21 - Head
"Sheesh, Buttercup, is that head full of muscles instead of brains?" Princess sneers, knowing that her lover will charge like a bull at the comment.
#22 - Hollow
One felt empty and unfulfilled as she was fussed over by the townspeople for yet another job well done, the other felt lonely and unsatisfied as she was handed another suitcase of money in lieu of any real affection; they made to enjoy it, but it left them feeling hollow inside.
#23 - Honor
Giving up my honor as a hero is a little too easy to do, she thought as she cast a longing look at Townsville's would-be Powerpuff and royal brat.
#24 - Hope
It's stupid to hope for a life together; Buttercup is well aware of that, but the thought still crosses her mind once in a while, a futile dream of happiness with the only person who gets her.
#25 - Light
There is a bit of light in Princess as well; sometimes, the rich girl will show a sense of compassion and sympathy that Buttercup would have thought her incapable of, only to have it vanish too quickly in the next moments.
#26 - Lost
Princess's mansion was huge: it was easy for Buttercup to get lost in there without Princess leading her; however, she soon became very familiar with the bedroom's location.
#27 - Metal
Beneath those plates of metal, Princess is really just a normal girl, perfectly vulnerable; judging by the way she acted, however, you would have thought her just as physically strong and invulnerable as Buttercup even without her armor.
#28 - New
It was very disquieting for Buttercup to realize that the person she'd thought of as an incorrigible brat wasn't that bad; when she looked at her with new eyes, she was actually kind of pitiable.
#29 - Old
The old rules still remained: lovers or not, they were still on separate sides and nothing would change that; a kiss could dissolve all too quickly into a fight on the rooftops.
#30 - Peace
A fragile peace hung over the air as the two girls, having exhausted themselves of insults to prod each other with, collapsed side-by-side on the couch.
#31 - Poison
Princess's words were often laced with venom and most of them were reserved for Buttercup, who could easily trade back equally damaging remarks.
#32 - Pretty
Of course Buttercup finds Princess pretty...beautiful, really, but she knows that any illusions of perfect beauty will shatter as soon as the heiress begins speaking.
#33 - Rain
Princess hated the rain- it made her hair frizz, she explained, which made Buttercup burst out laughing.
#34 - Regret
If the two had any regrets, it was that it ended in tears instead of the rancor it had begun with.
#35 - Roses
The gold roses were not complete without the green thorns on their stems, Buttercup informed Princess, who simply rolled her eyes.
#36 - Secret
The whole relationship is their dirty little secret...and they intend to keep it that way.
#37 - Snakes
Existing with Princess is like handling snakes, you hold the danger of being bitten.
#38 - Snow
The green Puff has the strength to throw a snowball into the sun, and the ability to make even the heiress raise an eyebrow.
#39 - Solid
"Go ahead, try to punch through it" Princess announced; Buttercup attempted to do so to her new battlesuit and failed- the thing seemed as solid as a diamond.
#40 - Spring
The confession leapt out of Buttercup's mouth before she could suppress it; Princess only smirked and nodded knowingly.
#41 - Stable
There could be no stability here, only unpredictability, war, and power struggles- how enthralling.
#42 - Strange
How strange it was that a romance could be formed over a struggle, itself based on jealousy!
#43 - Summer
The heat gave Buttercup an excuse to trade her jeans for a pair of cutoff shorts and Princess an excuse to stare at her tanned, muscular legs.
#44 - Taboo
Buttercup learned that it was not taboo that she loved other girls, but that she loved this girl, which only made the relationship all the more exciting.
#45 - Ugly
It was hideously ugly, Princess thought, regarding the bruise Buttercup had given her, but she supposed you could see it as the world's most twisted anniversary present.
#46 - War
This war between heroes and villains would never be over, it even boiled over into the bedroom.
#47 - Water
Her clothes were dripping, her hair lay soaked against her skull, her usual frown was deeper than usual, her wealthy lover exalted in knowing that the rain she so hated hadn't treated her well at all.
#48 - Welcome
She showed up often now at Morbucks Manor, but it was hard for her to get the sense of being welcome there.
#49 - Winter
They began with falling leaves and continued into falling snow; indeed, everything about them often seemed to be going on a downward course sometimes.
#50 - Wood
Love was like a beautiful, delicate flower, so Buttercup had been told, but she knew better- her love was tougher despite her beauty, with thorns and poison blossoms to match.