Something was wrong in Equestria, the naïve native ponies didn’t notice it, but Tempest was sharper than any of them. She had learned to spy rats and schemes behind every door. Her time in the Storm King’s army had been an entire hive of snakes, and Tempest had learned how to sniff them out.

And she knew there was something amiss, a secret kept amongst the guards, particularly here in Canterlot. It was like being a filly not invited to a secret club, the way conversations would stop when she approached, the way the guards would have meetings that she wasn't invited to, and were so evasive when she asked about them. On their own, these wouldn't be important, it wasn't as if Tempest was any stranger to being alone, but there was something more to these meetings. The evasive conversations weren't awkward, they were worried. They weren't worried about hurting Tempest's feelings (as if she cared about that) but instead they were afraid of consequences. Tempest knew the difference from serving the Storm King where incompetence could be punished brutally, the sweat that fell down their brow, the slightest shake of the body, they weren't looking to another for support because there was no question that Tempest shouldn't know the truth.

Worse, when she had started investigating, she found herself stonewalled at every turn, particularly amongst the highest levels of power. That meant the conspiracy to the highest levels of power, Celestia probably had some hint of it, but she probably didn't suspect how dangerous it was, it might be a coup. Tempest had few ponies she could trust, Celestia and Twilight were some of the few. Celestia wasn't going to coup herself and Twilight had been the pony who had once redeemed Tempest, so she owed her that trust, but other than that? Maybe Luna was behind it, she had done so before as Nightmare Moon, hadn't she? Or perhaps Chrysalis was working behind the scenes once again, replacing ponies with changeling doppelgangers? Or perhaps it was the dark unicorn Sombra? That last suspect was perhaps the one Tempest most suspected, as she had made her way back from Canterlot, she heard reports of a dark presence being summoned to Canterlot from the Crystal Empire, and hadn't Sombra been known to use mind control magic before? Sombra was her most likely suspect.

But ultimately, Tempest didn't have any guarantees, she just knew that something was happening, and that was a gut feeling, she just hoped Celestia wasn't too naïve to dismiss her reports. A possibility that Tempest was dreading as she made her way into Celestia's war room.

Meanwhile, however, in the secret chambers of Canterlot, another of Spike's slaves had arrived in secret to fulfill her Master and Mistress's plans. The dark mage Sombra, now turned into the dark sorceress Umbra, bristled at the idea that the dragon and unicorn would dare imply that they were her Master and Mistress though. In Umbra's mind, this was nothing but a convenient little alliance between the two of them. Sure, Umbra had used dark magics to change her form to that of a dark temptress but that was only so that she could manipulate Spike better. The dragon fool was so easily led around by his dick and the unicorn, her depraved fantasies, so why not take advantage of it, and besides, the sex was good....more than good...you might say amazing or perhaps divine.

BUT-it was all a means to an end. That was what Umbra had to constantly remind herself. It was so she could betray them at some point, take their power for her own, somehow and rule Equestria forever. Certainly, her schemes had not succeeded yet, and she sometimes would get distracted from making new ones but that was besides the point. She couldn't be expected to be scheming all the time, besides, the more power Spike and Rarity gained, then the more Umbra would receive when she took over. Even if it made her horny as hell.

So, when Spike and Rarity sent Umbra a message requesting her aid to enslave Tempest Shadow and after that, use her mind control helmets to remove whatever dissent remained in the Royal Guards, Umbra had different ideas in mind. It was fortunate for the dark unicorn temptress that Spike and Rarity liked to be creative with their pursuit of power, that they preferred to leverage the full power of their harem empire rather than simply ask a question. They enjoyed being creative, and using their power. Umbra could sympathise, though this would be their downfall.

If only Umbra knew that Spike had used the Root of Honesty to make her plans backfire in his favour.

Umbra arrived at Canterlot, eager to put her plan into motion. Umbra had studied Tempest Shadow well, particularly her time under the Storm King, and why she might have served that Yeti King, and Umbra felt that she could tell what truly motivated the unicorn. With a dark charm, Umbra summoned a glamour around herself, taking the appearance of dear Twilight Sparkle. In no way was this glamour as effective as changeling magic, but for now it would be enough to fool the unicorn.

The doors opened and Tempest Shadow marched in, still wearing her Storm King uniform. Umbra had heard that the former Storm King lieutenant didn't think the Royal Guard uniform was in any way sufficient. Perhaps if Gleaming Shield changed those outfits so that sex appeal wasn’t favoured over function and survivability, stupid in theory, but Umbra had known the true purpose behind them.

"Princess Sparkle." Tempest said, head held high, her back straight. No other pony addressed Twilight as 'Princess Sparkle', such a formal address was unique to Tempest Shadow's strict nature. "Thank you for meeting me on short notice. I need to apologise for such a sudden request."

Too formal for Umbra's liking, and from what Umbra had learned from the times she had fucked the Slutprincess of Friendship, most likely too formal for Twilight Sparkle as well. "As I've said several times before, Tempest, call me Twilight."

"Very well, Princess Twilight." Tempest Shadow answered, her back and stiff and strict as it was before. "I have an important report, I have reason to suspect that there's whispers of a conspiracy within Equestria, perhaps even a coup."

Umbra couldn't help but flinch, her Master and Mistress's conspiracy had been found out! But it was only for a second before a savage slither of pride filled her, Celestia hadn't been as careful as she thought...and perhaps she could use this to her advantage. Yes, turn Tempest against the others, bring her under Umbra's sway and take the Royal Guard for herself. Yet, she should know just how much Tempest had found out.

"What makes you say that, Tempest?" Umbra asked, playing the role of the naïve, innocent fool that Tempest expected to be. "The ponies are all so trustworthy."

Subtly as Umbra playing the role of the Slutprincess, she used her own dark magic, probing Tempest's soul for weaknesses, angles for corruption. It wasn't a precise magic but she could get on the right track. It seemed that Tempest had some dark fetishes and that perhaps her old loyalty for the Storm King wasn't only because of a broken unicorn horn.

Unaware of Umbra's probing, Tempest simply laid out her report onto the table before her. Not unlike the real Twilight, she had her papers organised impeccably, not a single spelling mistake, crease or imperfection in the papers. "I have nothing concrete as of yet, but there have been details, rumours and I've been noticing things."

Tempest's report was long and detailed. She reported on specific times she had noticed ponies whispering amongst herself, times she had suspected her reports were being covered up by those in high positions, and rumours of a time to strike. These must all be the guards that Gleaming Shield and Celestia had corrupted over the years, and the higher ups must be the agents of L.U.S.T. Tempest Shadow was on the right track, but she was just missing the mark on the true reason, and the true depths of how far it went.

"Don't be so worried, Tempest." Umbra said, in the same soothing tone Twilight would often use. "We'll get to the bottom of this, but I think you're being paranoid.”

Tempest Shadow's nostrils flared, and Umbra knew she had hit a nerve. "Paranoid? This is why Equestria has been invaded so many times these last few years. Have you forgotten Sombra's attacks? Or Chrysalis at the wedding? Or her kidnapping your friends and replacing them? Or the Storm King?"

"That last one was because of you." Umbra reminded her, a statement designed to pierce through Tempest's façade. To turn her frustration to guilt, guilt that Umbra was able to corrupt.

It worked. Tempest Shadow flinched, those feelings distracted her from the report and the unusual tone of accusation in 'Twilight's' voice. With Umbra's magic she sensed that this was a weakness, an avenue of corruption to bend her to the dark mage's rule. "Y-yes, Twilight. Please, this is why-"

"You never told me why you served the Storm King for so long." Umbra stared, her eyes glowing green even through the glamour of Twilight Sparkle. The corruptive magic began influencing Tempest's soul, causing her to overlook them. But they poured Umbra's dark magic into Tempest, fuelling the dark flames that simmered in Tempest's soul. A dark flame that had long been smothered with guilt and remorse but still burned all the same.

"I told you this already, Twilight, after my horn-"

"There was something else wasn't there?" Umbra interrupted, the sharpness in her voice sending shock rippling across Tempest’s face. "Something you didn't tell any other pony, something more primal and shameful."

Tempest's gaze turned to the floor, afraid that her eyes would betray the truth. "It-it's hardly important."

The shame and the desire to avoid Umbra's gaze only made the unicorn more vulnerable. Umbra's dark magic poured into Tempest's soul, like metal dust to a magnet. The dark, sinful flame in Tempest's soul started to stir, growing slowly brighter even as Tempest tried ever harder to deny it, to bury it, but she only succeeded in fuelling it ever more.

"I disagree, sweet Tempest. It's important to be honest, to confront the truth. To be yourself, to be your REAL self." Umbra purred, her words infused with dark magic. Not nearly as potent as other means her Master had to corrupt and control, yet the magic gave her words…impact.

“There was indeed something else, a deep seated...allure.” Tempest confessed. This ‘allure’ had probably been such a small thing, a mere afterthought in a storm of isolation, loneliness, bitterness and despair, but Umbra's magic fed into it, making it burn brighter in her mind than it should have. This was Umbra's opening.

Still disguised as Twilight, Umbra strode towards the unicorn, making sure to shake 'Twilight's' magically enhanced tits with every step she took. "Oh, do tell me more Tempest. After all, true friends share EVERYTHING with each other."

Tempest visibly swallowed. "The Storm King was a cruel tyrant, yes. But he was strong, decisive, powerful, it drew me in to him a little. He was... Celestia, I sound like a slut..."

"Nothing to be ashamed of." Umbra purred, stroking Tempest's arm with her own. Her touch was, by design, teasing and sensual, yet just innocent enough to maintain plausible deniability. "You're in good company, I assure you."

"He was hung as well, he made that clear." Tempest whispered, her tone was on the verge of confession. "Perhaps there was a part of me that was...that was..."

"A size queen?" Umbra purred, her grin now threatening to split her face in two. "Or was it his power, dark nature, and willingness to take whatever he wanted?"

Umbra could hardly believe her luck, what a perfect little fetish. A corruption that could be fuelled into a weakness, and perhaps Tempest's little thing for villains could be co-opted towards a dark sorceress. And wouldn't Tempest make such a useful right hand for her Mast-HERSELF! Umbra meant she'd make an excellent right hand woman for herself.

"I can see the allure, it's intoxicating. To serve the powerful, the strong, to be there as you bring the world to their knees, with you serving by their side." Umbra purred, her arousal starting to get the better of her. She couldn't help herself; this was Umbra's fantasy as well. Could she sneak a hand under her dress, to sooth or perhaps stimulate her aching pussy? Could she risk it? She shook her head, needing to focus. "Perhaps the Storm King betrayed your loyalty, your lust, but perhaps another dark villain wouldn't be so treacherous."

Umbra closed the distance between them, 'Twilight's” mouth curled into an evil smirk. Tempest's eyes widened in fear, realisation was dawning on her face, she knew something was deadly, deadly wrong. Yet it was too late for her now, Umbra's corruption had her hooks into the unicorn now and she wouldn't let go no matter what. She might not be able to rewrite her from the ground up like her Master could with the Root of Honesty, at least not without her mind control helmets, but the corruption had her trapped. The good parts of Tempest's mind were being closed in, trapped in a inferno of corruption. The small flame that had once burned no brighter than a birthday candle was now spreading wildly, and would not be smothered easily.

"You're not Twilight." Tempest Shadow gasped, her voice shaky. Her knees wobbled with arousal, her fur started to shimmer with sweat. “Who are you?”

Grinning like a wolf, Umbra dispelled the illusion. Tempest’s mouth widened in horror and her horn fizzled with magic to defend herself, but of course, a broken unicorn horn was no match for Umbra's dark power. In fact, Umbra didn't feel the need to even dignify it with a response. "I was Sombra, but as you can see, I've had some improvements..."

Umbra's hands roamed down her body, trailing across her huge dark breasts, her wicked hourglass figure, powerfully wide hips. She was the epitome of sexual, dark allure and while she might not have dominating dick like the Storm King had, (even when she had been Sombra but she wouldn't tell them that), but Umbra's body still stirred all the dark flames that Umbra's magic was fanning in Tempest's mind. "Perhaps, you might also be tempted with a dark, wicked temptress?"

Chrysalis had told Umbra all about how she had seduced the child of Spike and their enemy Cadance's daughter, how the Changeling Queen had leveraged dear little Rose's fetish to gain power. To bring Daybreaker and Nightmare Moon into power, whilst also gaining two Hatchling daughters for her plans. Perhaps Umbra could do something similar here?

Umbra strode forwards, closing the distance between herself and the horny unicorn. Tempest's magic cackled from her broken horn, unstable yet unrestrained and more powerful than most. Nevertheless, Umbra didn't dignify Tempest Shadow's desperate attempts at resistance with anything more than a raised eyebrow. She was out of Tempest's league and she wanted the unicorn to know it. "Perhaps there's a part of you that craves to serve a dark lady of conquest? One who'd recognise what a wonderful sex toy you are, and would never throw you aside callously."

"I-I-" Tempest stammered, but then her resolve hardened with one unbreakable barrier. "I'm straight."

Umbra tsked, her teeth were bared into fangs. That was a problem, a single unstoppable fact would keep Umbra's corruption contained. Frustrating, but Umbra couldn't change to a stallion even if she wanted to. After all, a dark enchantress like herself needed a beautiful body to tempt and arouse her targets, like that sexy dragon stud. How could she serve her Master Spike half as well without a sexy dark pair of tits to wrap around his cock?

Wait, NO! She didn't want the damn body to serve that damn dragon, but to control him and to control any other stallion she met. She needed this body that was thrumming with dark allure for the power it gave her, and for the games she could play...but perhaps that dragon could be useful. After all, he was hung, sexy and powerful and Umbra was certain that eventually she would have him under his control. After all there was no way she was passing up a dick that good...

She slapped herself- FOCUS!

"Hmpff..." She snorted, pretending this was no major setback. No perhaps this was an advantage, a way to corrupt Spike and make him do as Umbra wanted. "Maybe you are, but that won't satisfy your Master, my sweet pet. You must learn to lust after the female form in reverence for the Master you secretly crave. You must be ready to fuck glorious goddesses like me so that your dragon master can be truly pleased, to entertain his every fantasy."

"Yes... a sexy, dark dragon Master. One with a huge cock to conquer me with, to use me as a pawn to conquer all others. For a Master like that, I will fuck other women for his pleasure." Tempest moaned, falling once again to Umbra's corruption. Good this was a weak point, she might not be able to change the unicorn's sexuality outright, but it could be twisted to serve a male Master. It was a start.

But this would be tricky, now Umbra could not twist Tempest to serve the dark Queen directly. No, instead she would have to make Tempest serve a male Master to begin with, and then have that male Master serve Umbra. Eventually, Umbra would find a way to dominate her Master Spike and his diamond Rarity...eventually. It would take time but she’d find some way. For now, Tempest must serve.

“Yes Tempest, think about a powerful dragon Master. A cock more powerful than any other, able to break and ruin any mare he penetrates into. His stamina is unmatched, I believe that if he wanted to, he could plough his way through all the mares in Equestria in a single go. That, my dear, is true power. Ultimate power to conquer and ruin." Umbra whispered into Tempest's ear. The Dark Queen had no need to act seductive nor aroused, both came naturally to her as the thoughts of her dragon Master made Umbra's blood run sinfully hot. "He could take you, make you his own. Make you his slut slave at the head of his new Empire."

"Yes, yes, FUCK!" Tempest moaned, her hands clenched down her legs, unable to break through . Her mad lust had driven her magic wild, enough that it had trickled down Tempest's own armour, weakening the steel. Umbra smirked, how desperate her body must be under that armour? It seemed only natural that Umbra relieve the desperate unicorn.

Umbra's dark magic struck across Tempest's armour like a knife through a dress, even the Storm King's armour no match for Umbra's dark magic. It crumbled to the floor in several pieces, flying off as if Tempest's body magically repelled the armour under the sheer force of her arousal. No sooner had the armour flown off her body did Tempest's hands surged to molest herself, so ingrained was Umbra's magic that the dark flame within her made her skin burn as hot as true fire. Tempest fell to her knees, her dignity gone, all she cared about now was her pleasure and her debasement.

[Derpibooru: 3278695]

The iron was hot, and it was time for Umbra to strike. "It's been so hard, hasn't it? Pretending to reform, pretending to care about ponies and principles. The kindness, good and nobility in your heart, what has it gotten you? A broken horn, an exhausting job and a boring life. You would be better without it, Tempest, better without the good in you. Better to be bad, a very sexy bad."

The timing was perfect, and Umbra knew it. She could feel Tempest's resolve cracking. Umbra's corruption was hammering what remained of the unicorn's defences with the force of a sledgehammer and they were crumbling like dented iron. It wouldn't take long for it to crack completely. Umbra clenched her fingers, and she summoned one of her favourite mind control helmets. They were so much more thorough than her bare magic.

Tempest recognised the helmets, even in her cock-drunk state. Even as her tongue rolled out of her mouth, her eyes opened in horror. “T-those are-“

“My signature mind-control helmets, able to penetrate much deeper into your mind. Able to bury themselves deep into your subconscious, to change yourself from the very bottom of your heart, to serve your dragon Master." Umbra whispered into Tempest's ear. One day, Umbra would need to place one of these helmets on her Master's head, reprogram him to serve her. But that would come later, for now she had Tempest to conquer. "And with this we can wipe away your old, prudish shame, and let you become what you really want to be!"

"But...I'd be controlled, enslaved. Unable to think for myself, at your complete mercy. I would be reduced to..."

"To a slave, a fucktoy, a weapon of lust and depravity. My Master's sexual weapon, betray Twilight's trust and become mine!" Umbra practically roared the last words into Tempest's ear. The final push she needed to break through Tempest's final mental defences. It started slow, but with trembling fingers and a heart filled with sin, dark magic and lust, Tempest wrapped her hands around the helmet.

"I...I can't...Twilight's trust..." Tempest whimpered, but her body betrayed her, and not just her sex but also her hands. They took the helmet and with her judgement distorted by Umbra's dark corruption planted it on her head. "But I need this...do it."

The magical helmet sealed around the unicorn's head, and Umbra let out a bark of triumphant laughter. She'd done it, she was hers! Nothing could go wrong now!

But it was right at that moment that her curse kicked in.

Author's Note

Special thanks to Jonathan Stag for the idea of making Tempest Shadow a closet size queen that could be manipulated. And CrimsonS4ge for the idea to use Umbra. I have a loose idea of what comes next now, but I'm always happy for more ideas.

Any suggestions, feedback, and constructive criticism are welcome.

And special thanks to ShadowLDrago for proofreading this chapter.