Sexy Brain Parasite Story

by Damaged


A Siren Undone

Laughter—a little hysterical, but mostly mirthful at Luna's request—poured from Sonata's mouth. "You really want to narrow things down just a skosh. Do you want to know about my time in Equestria? Or do you want me to start after we got sent here? Oh, oh! There's the really short version, it's just from when we noticed the pony magic here."

Glancing up at the clock, Luna let out a sigh. "Background, as much as you think is important, and all recent events that pertain to your change of heart." Reaching into the top drawer of her desk, Luna pulled out a little voice recorder. She tapped the record button and set it down between them. What Sonata didn't see was Luna touching the intercom button that led to her sister's office.

"Oh boy. Where to start?" Sonata slumped back in her chair and lifted a hand up to support her chin. "Might as well go all the way back. So, in Equestria, the most important country in the whole world is Equestria, and it is full of ponies. Me, Adagio, and Aria used to swim around the edges, finding ships of ponies and we'd totally sing them to fight each other. It was funny at the time."

Luna noticed a distinct look of regret on the girl's face. "But it isn't funny now?" Of course she knew of ponies, and had already decided to just let that slide without query.

"Those ponies got really angry. Some fell off the ships." A shiver ran through Sonata: that wasn't a time she was proud of, now. "Flash forward a little. We got bolder, traveled inland. No ponies going overboard anymore, which was good, but we were really nasty. So a group of brave ponies tricked us into flying into a portal.

"They sent us here. No magic. We still had some oomph from our last meal, and we used it as sparingly as possible. Sonata was all about getting back to Equestria, but…" Sonata trailed off, staring down at the table. "I like it here. Humans are way more interesting than ponies. For a start, there was all this different music!"

Sonata had become much more animated, Luna noticed. "How long was it until you noticed our school?"

Giggling, Sonata had to cover her mouth. She stared at Luna for a few second, and held up her other hand in a halting gesture to forestall interruption. "Hold on, there is some math to do here… About one thousand, two hundred and five years." The look on the vice-principal's face was everything Sonata ever wanted to see at that moment. "Give or take a few months. Anyway, I kept trying to make friends, and my sisters kept dragging them into their schemes. It started to wear me down.

"So we got bored in Europe and came here. Found the same kinda stuff, and I felt like a zombie, you know?" Sonata looked at Luna, expecting a nod. When the acknowledgment didn't come, Sonata blew out a sigh. "You know, walking around, going through the motions, but not finding anything really fun anymore?"

When Luna just nodded, Sonata continued. "And then Adagio sees a rainbow shooting up into the sky, and makes big with the promises of taking over here. I think even Aria was starting to get a bit sick of her by now, but we followed her here." Sonata hung her head, the next was probably her worst moment.

"You worked your way into the school, you took control, then you started the concert and heard Fluttershy's song." Luna actually smiled as the girl looked back up. Sonata might be over a thousand years old (if she were telling the truth) but the look of heart-warming pleasure was clear.

"Fluttershy… She is the shy one?" For a moment Sonata felt fear, as all the humans she had liked over the last millennium paraded in her head and were gobbled up by Adagio's magic. Then she remembered not only was Adagio and Aria gone, but they were powerless too. "I owe her everything. From the moment her song started my heart changed beats. Adagio signaled the attack, channeled the magic we had to transform us, and I pulled every punch."

Luna leaned forward, looked into Sonata's eyes to study the girl and hopefully figure out if she were lying. "You implied that before. What do you mean exactly?"

"Simply that. I held back. I was still singing, I still used up my share of power to transform and everything, but when Adagio signaled for us to put our magic into our voices, I didn't. I couldn't." When Sonata closed her eyes, she could still hear the songs in her head. It wasn't just a trick of her mind, it was real magic—pony magic. "We defeated waves of pony Royal Guard. We caused the most stoic and loyal to fight among themselves. We almost defeated the greatest heroes Equestria had ever known. Six girls and a young pony princess were no match for three sirens.

"Don't get me wrong, they defeated us fair and square. But they didn't defeat us the way they thought they had." Sonata felt comfortable in admitting such, even happy that it was her heart they had taken down. "Adagio wasn't happy. She took it out on me, mainly, because she knew what I had done. It was the last straw, and when she announced we would go and try to make new gems, I told her to put her new gems where they wouldn't fit too well. I wanted to say I was sorry, I wanted to show it, but when you have no money and nowhere to live you have other preferences first.

"I started doing work, sweeping around shops, helping people lift and carry things. They wouldn't pay me a lot, but it was enough to live on."

Luna was struggling to take everything in, but managed to keep up with the story. "Where were you living?"

"Wherever I could. Usually I would do some work for someone late in the afternoon, and ask them if I could sleep on a porch or something. I have a real job now, and a room to sleep in is part of the deal." Sonata couldn't be happier about her deal with Spicy, particularly since it had led to her meeting Rarity.

As Sonata's happiness seemed to fade away, Luna raised an eyebrow. "They aren't taking advantage of you, are they?" Her tone had been sharp, and she realized that if something was happening to the "girl," she would get every bit as protective as she was about her students.

"What? Oh! No!" Sonata forced a laugh at the notion of Spicy taking advantage of her. "Spicy—my boss and landlord—is great. I just thought of Rarity again, and…" A hand reached across the table and took Sonata's.

"She'll be okay. Rarity can take care of herself, and I don't think her parents would let something bad happen without defending their girls." Luna's mind switched gears. She realized how experienced with music Sonata likely was (given her age), and the desire to have her in Nightmare Moon—it had become a collective name—was high. But giving Sonata a spot in a band, after what had happened, didn't seem wise. "I think I am satisfied with this." She reached out and turned off the recorder.

The door to Luna's office burst open, and a small flood of teachers froze in their tracks as the sight of Sonata. Each of them held the roll lists for their classes, and not a single one would enter Luna's office.

"It's alright, no need to be alarmed, Sonata is here to apologize." Luna turned her gaze from the shocked teachers to Sonata. "Aren't you?"

Sonata lifted her head and nodded. Swiveling around in the chair, she stood up. All the teachers fell back a step from the doorway, and she realized how much harm she and her sisters had done. "I'm sorry for what we did. We had no right to—to attack you like that." Sonata turned to look at Luna, and got an encouraging nod—she turned back to the teachers. "I hope you can give me a second chance, but I need to warn you, all of you,"—she glanced back once at Luna again, to include the vice-principal—"my sisters are still out there, and they are really annoyed."

"They're annoyed?" Cheerilee couldn't help asking a question, it practically begged her to say.

"Because they lost, and they lost their gems." Sonata grinned widely and gestured to her unadorned neck. "No more magic!"

Cheerilee felt compelled to ask more, particularly since Sonata Dusk was sitting in the vice-principal's office, and that is where students were usually signed up. "Are you going to be starting here?"

"What? Oh, no!" Sonata shook her head for emphasis. "I came here to apologize to everyone, and make sure a friend is okay. I guess we are done with that now, right?" She looked back at Luna.

"Sonata, it's a brave thing coming here. If you ever need help…" Reaching to the little stack of stationary she kept in her top drawer, Luna produced a card with her business number on it. "This is a step in the right direction."

Taking the card with an odd amount of gravity, Sonata nodded. "Thanks. Uh… If Rarity arrives, can you please have her call my, uh, work?" Looking around for a pen, Sonata spotted one and then had the conundrum of requiring paper. By then, however, Luna had divined her intent—supplying a notepad. Sonata scribbled the work phone number on the pad without a thought. "Call, and ask for me. There's only two of us working there, so Spicy could take a message if I'm not there."

When Sonata walked to the door, she noticed the teachers didn't pull back so much as made room for her to leave. She managed a smile for them, recognizing a few as present at one of The Dazzlings' performance or another, but there was another target for her attention.

Sonata didn't make for the school exit, she walked across the hall to the principal's office. Lifting her hand to knock on the open door—as a courtesy—Sonata was startled when the woman who looked most like a near-goddess in Equestria looked up. "Uh, hi."

"Sonata Dusk. I overheard your little speech, come inside." Celestia felt a slight pang of worry, and readied a few pens to throw if she saw the girl start singing. "Why are you here?"

"T-To apologize. I did some—a lot of—bad things, and I shouldn't have, but my sisters were pushing me. I wish I could go back in time and make it all better, but it took the Rainbooms' music to make me see what I was doing had to stop. So I'm sorry." As she dipped her head down, Sonata wished she had the fortitude to do this before Equestria's Celestia, but in this place Principal Celestia was the highest power she could appeal to.

"I heard. I agree with my sister's assessment of this, and for your sake I hope you are being completely truthful." Reaching to the papers on her desk, Principal Celestia made a show of straightening them. "That you were partly a victim in all this too is encouraging, and if what you said about your sisters is true, I think it would be a good idea if we kept in touch. You have Luna's work number,"—Celestia reached to her own stash of business cards and passed one to Sonata—"now you have mine. If you ever see your sisters back in town, call both of us."

Support was the last thing Sonata had ever expected to get, but she suddenly realized it was the most precious thing she could receive. She nodded, not trusting her voice.

"Now, please only visit before or after classes, and report in here first." Celestia had to do her more stony, principal face to make sure the instructions got through. "Unless it is an emergency, of course. Have a nice day, Sonata Dusk."

It was a firm dismissal. Sonata retreated from Celestia's office and walked from the school. The moment her foot reached the pavement outside, however, her worry for Rarity returned.


Deep in an induced coma, Rarity's mind was mostly quiet. Slowly, the parasite within her head stretched out and secured itself more and more. It was actually working faster than usual because of the increased noise around its host.

Normally, it would take two full days to fully infest a host's brain, but when the loud thumping sound came again, the parasite began adjusting its host's sleep, slowly bringing Rarity to a drunk-like half awake state, and then pulled away the melatonin completely.

Rarity jerked upwards in her bed. There was banging coming from downstairs (her bedroom was right over the front door). Something felt unquestionably odd to her, and as she heaved her legs around to stand up, she leaned sideways from the bed and emptied the contents of her stomach onto the floor.

Staring at the mess she had made, Rarity was surprised by how little she had lost. The banging at the front door startled her from her introspection, and she jumped up and started to run for her bedroom door.

Freezing in the middle of her room, the confused fashionista stared down. "I never sleep naked." She looked at her smooth, white breasts, and lifted a hand to stroke one. She didn't know why she was rubbing herself when she needed to get dressed and answer the front door, but here she was. "I need to get dressed, this is simply too—too surreal."

With the practicality of a young woman who frequently has to ignore her fascination with fashion to fight interdimensional monsters, Rarity grabbed a bathrobe and pulled it around herself.

Walking out of her room, Rarity was overcome by how quiet the house was, apart from the banging. "Must have all gotten up early." She walked down the stairs and reached the front door. Leaning to one side to peek out through the glass side panels, she was suddenly blinded by a bright white light shone in her face. "Ugh!"

Fumbling at the door lock, Rarity opened the door. Squinting at the bright light, she narrowed her eyes enough to notice a blue uniform that looked like it was made of cotton. The buttons were utilitarian, the folds conservative, and Rarity simply couldn't abide by the turned-up sleeves. "Can I help you, officer?"

"We had a report from the school that something might be wrong at home, ma'am. Is everything alright inside?" The officer had been banging on the door for the better part of fifteen minutes, and had been in the process of searching for probable cause to break in when Rarity opened the door.

Rarity stifled a yawn, and couldn't take at least part of her mind away from how good the soft fabric of the fluffy bathrobe felt against her breasts. "Hrmm? The school? Why would they be checking up on us? It's only Sunday morning."

Confusion reigned, and the officer scratched their head. "Ma'am, it's Monday evening. The vice-principal said you had missed a final today. Ma'am, have you been drinking?" Rarity had run away from the door, and he assumed it was to check the date and time. When the officer heard the most pained scream of their life, they shoved at the door and reached a hand to their sidearm. "Ma'am! Are you in trouble?!"

Turning from the fancy oven clock in the kitchen, Rarity poked her head into the hallway to the front door and spotted the police officer looking around, gun drawn but aimed to the floor. "It's Monday! Monday night! I missed my final!" Her eyes fixated on the officer, and locked onto the gun. "W-W-Why do you have your gun out?"

Realizing their assessment of the situation was possibly in error, the officer quickly holstered the gun. "It's understandable, if you lost two days. Any idea what happened?"

Panting in shock, Rarity looked up at the officer's face and did a double-take. Female officer. She blinked her not-fake lashes at them and looked down, then back up. "If it weren't for that tight cotton—" Rarity quickly clamped her hand over her mouth. The parasite in the girl's head was barely taking notice of her preferences yet, and was more concerned about having the other—potential—host leave.

"I-I'm sorry. That was completely inappropriate, and I shouldn't have said it. I must be out of sorts from—from whatever caused me—us—to sleep that long. It must have been a freak case of the flu! That would do it." Rarity didn't often ramble when she spoke, but trying to make an excuse for her behavior, particularly that behavior, deserved some good rambling.

"Right! Flu! Of course." The police officer stole a glance back towards the door and did everything in her power to ignore the pass a highschooler had just made at her. "I'll have to go and report it. You uh…" She backed up, found the door, turned and ran.

As the officer ran for her car, Rarity noticed—and couldn't stop noticing—the firmness of the woman's rear. Her tongue snaked out the corner of her mouth, and Rarity was licking her lips before she realized it.

Only snapping from her daze when the officer was out of sight, Rarity felt a burning need in her body that had one hand slipping inside her bathrobe even as she stepped forward to close the door. Turning the lock, she stared blankly at the door as her hand kept up its massage. In her head, her parasite was stirring her towards pleasure, wanting the food it now desperately needed in order to completely finish its efforts.

Walking in a daze, Rarity's bathrobe fell open, and with one hand massaging a breast, her other slid down her body to her groin. Soft whimpers and a little gasp left her throat as she walked upstairs. She found her bedroom and her vagina with a finger at the same time.

Walking into her room, Rarity ignored where her pet was curled up on the bed, and curled up on the covers. On her back, Rarity's fingers formed a V pattern, and she slid them down with practiced precision to catch her clitoris. For her, nothing worked as well as directly working her clitoris.

Starting a steady wail of moans and squeals, Rarity stroked her body to orgasm, then another, and a third before she passed out. In her head, the parasite was pleased with its host, and eased her back to deep sleep with more melatonin.