I can't call this fanfic and I'm not actually a fan of this show. I'm just a hack delivering stories to my audience.
The Nightmare MonsterDarcy was tired of Icy and Stormy pushing her around. This time, she would show them up. She would show them that she and her illusion powers were just as good as their powers. To do this, she delved into the most powerful magic that she could find, and there discovered how to summon a nightmare monsters.
Summoning the nightmare monster would be difficult. It would require far more power than she could command on her own. She would need all the power that she could arrange, and the best way to do that would be to give nightmares to all of Cloud Tower. So that night, after everyone was asleep, she slipped down into the tunnels beneath the school and set up her spell, making sure that all of Cloud Tower slept poorly that night.
Icy and Stormy got the worst dreams. They both found themselves in places where their powers didn't work and everything was pink and cute. Icy railed at this dream. "I hate pink and cute."
When Darcy had enough power, she channeled it all into her dark spell, summoning the nightmare monster, half real and half dream. The back half was real while the front half was dreams.
The Winx were warned something might be happening as the dream monster was so strong, that even at a long distance, the creature invaded their dreams.
"I had the worst nightmare," said Musa, "I was trying to practice my solo, but I kept spotting something out of the corner of my eye. I just knew that it was coming to get me."
"I had a similar dream," said Flora, "My plants were dying, and I was trying to revive them, but the harder that I tried, the more that they died. And then, I just knew something was coming after me next."
"Same here," said Stella.
Techna did some math. "According to my calculations, this is statistically impossible. We should not all have the same type of dream at the same time."
"That means the Trix," said Bloom.
"It doesn't feel like the Trix," said Stella, "I don't get Icy's cold feeling out of this."
Just then, the nightmare monster arrived. It peered in their windows. The next thing that Bloom knew, she was trapped in her room by a fire, and she was tiny, and her small voice could not call for help, and she could not transform. She shook harder and harder until she realized that Stella was shaking her. "Snap out of it, Bloom!"
Techna stabbed at her device. "I've put up a dream dampener around us. It won't stop the nightmare, but it will slow down its affects."
"According to my reading," said Musa, "Nightmare creatures require huge amounts of power. If Icy isn't involved, I don't know where they're getting it. These things are difficult to impossible to control."
"That's its weakness," said Stella. "They're controlling it from the tunnels. You know them best, Bloom. Get down there and stop them in their tracks. We'll stop the nightmare monsters here."
Down the halls, they heard the other students screaming as they began throwing spells after imaginary foes.
"They're going to hurt each other," said Bloom. "I'll take care of this." Bloom transformed, then flew down the hallways casting her sleeping pollen at all the students. Soon all were too asleep to hurt themselves or each other.
"Let's distract this monster," said Stella.
They all transformed then flew out. Musa, Flora, and Techna dodged around the creature, attempting to stop it from behind, but before they could attack, the creature's tail slapped Techna, sending her through the huge windows of the dining hall.
"You need a little cheering up," said Bloom. "Daisy Chain!" A chain of daisies wrapped around its feet and tail, but that did little good. The thing's tail could not be tied up and it no longer cared about walking. It waved its tail at Musa and Bloom, who both dodged.
"I've got it," said Stella. "Let's cheer everyone up. Have a rainbow! Rainbow is the new pink, which is the new black. Is pink still it? Is it still the new pink? Or would it be the new black?"
"STELLA!" yelled her friends, "Cast."
"Oh, right," said Stella, covering the nightmare monster in rainbow.
Even as her friends fought on, Bloom flew through the tunnels. "Which way?" she thought. On noticing that some tunnels looked more dreadful than others, Bloom figured that she should always head for the most dreadful tunnel. Soon she found herself at the center of the disturbance. There stood Darcy, controlling vast a black magics.
"Dragon fire!" yelled Bloom, sending a burning attack through the energies, severing the witch from her spell. A vast black boom covered the room, sending both Darcy and Bloom flying against the walls. When the light cleared, Darcy lay unconscious.
"You'll have to stay there," said Bloom, "I have a nightmare to fight."
When Bloom arrived back at Alfea, the Winx were busy throwing everything that they had against the beast. By breaking the control spell, at least Bloom had made the nightmare creature all real.
"A little dragon fire will burn away this nightmare," said Bloom. With a big gout of flame, she ripped apart the darkness, leaving nothing of the creature but a few stray motes of darkness.
With the battle over, the Winx went back to their room and made sandwiches and tea. After a good midnight snack, they went to bed.
Over in Cloud Tower, Miss Griffon summoned Darcy to her office first thing in the morning.
"Young lady, that spell that you threw yesterday was the most insidious, low, despicable, and hateful thing that I've ever had the misfortune of beholding. My congratulations. More students should have your ambition. You're still in trouble, but not too much trouble. Just sweep my office, and next time, don't screw up your plan."