Twilight's Very Unusual Night Out

It was just a regular and boring day for Twilight Sparkle and Starlight Glimmer, reading various books and spellbooks to pass the time away.
The purple mare sat at her table in the Mane 6's throne roon inside her castle while wearing a sports bra for her single D sized boobs and a size 32/38 size sweatpants, reading a spell book on " Mare anatomy and Mare Asset Adjustments".
Twilight finds the spell she was looking for, which was a "Sex Drive Enhancement Spell".

She read the instructions needed to properly cast the spell right but she just needed a couple of test subjects to make sure that the spell worked and was safe.
She called for Starlight Glimmer.

Starlight Glimmer walked into the throne room and approached twilight only wearing a pink bra and army camo colored panties.
Starlight stood there while Twilight got up and looked her over.

Twilight notices Starlight's huge and lucious,light purple double-D sized boobs and her small and tight butt sticking out of her panties.
After a few minutes of walking Twilight and Starlight Glimmer sits down at the big round table that contained the friendship map inside
of it. Starlight was very confused.

"Why am I here again,Twilight?, If it was that incident with my old village, I promised you that I changed from that incident!", Starlight said

Starlight looks at twilight with a guilty smile on her face.
Twilight looked up at Starlight for a quick second and returned back to reading her spellbook.

"No, not because of that but something completly different than that Starlight",Twilight replied

Twilight closed the book and sat it on the table in front of her throne room chair that she was sitting in.

Starlight just sat there with an eyebrow raised as Twilight got up and assumed the position to start casting a spell.
Starlight started to get up very slowly, and almost acted like she was gonna start running.

"I need a test subject for a new spell that im trying out and I thought you were perfect for it", Twilight said

*Twilight smiles and claps her hands in excitement*

"Ok. But what the hell is this spell called, if I may ask?", Starlight replies

*Starlight Glimmer flips her hair back and places her hands on her hips*

Twilight looks at Starlight and motions her to get Spike from his room.
So, Starlight Glimmer went to Spike's room to fetch him and returns to the throne room with him.
Twilight looked up as Spike walked up to twilight and hugged her. Starlight was shocked at how tall that Spike was!

For a normal dragon being at least 5ft tall during their teenage years was common, but 6ft tall while they ar 17yrs old was highly rare!

"Hey Twilight, what's up?", Spike says jokingly

*Spike smiles at Twilight as he releases his loving embrace hold *

Twilight laughs at the joke he made and motioned him to exit the room while Starlight and her had a little chat.
Spike shook his head and walked out of the room for a little bit. Twilight hands starlight a lifelike costume of Rarity and told her to put it on.

Starlight took the costume and slipped it on.
Twilight then styled and dyed Starlight's hair to make it look like Rarity's Hairstyle.

"Why do I look like Rarity,Twilight?", Starlight asked

"You didn't know that, Spike, will only have sex with Rarity or somepony that looks like her!",Twilight shouted

Twilight walked over to Starlight Glimer and slapped her on the top of her head very hard.

" I need you to do this so that this spell will work", Twilight continued

Starlight grabs the top of her skull in pain, slowly rubbing it to ease the pain temporarily.

"First thing, OW! And the Second thing, What spell is it that you are trying to accomplish? You still haven't told me about it,Starlight said

"The spell says Classified,I read it and it says that it makes a Mare's Sex Drive last longer during sexual engagement, Even during an orgasm.
But the spell was very specific that it needs a male,a female and a unicorn to cast the spell", Twilight explained

Twilight hands the book to Starlight to let her see the spell for herself.

Starlight reads the title to herself and flips through a couple of pages and hands the book back to Twilight.
Starlight let out a huge sigh and Twilight called for Spike to come back to the throne room for a surprise that she had for him. Spike opened the door and walked in and stopped dead in his tracks.

Spike was lovestruck when he saw what appeared like Rarity standing right in front of him.
His dragon shaft immediately stood up in an erection.
Then Twilight casted the spell on both Starlight and Spike to see what would happen before she tried it out on herself.

After waiting for about five minutes, the spell started to take effect.
Starlight ran and jumped on top of Spike tearing his pants and underwear clean off and slowly sat on his monstrous dragon dick silently squealing because of the insert of his dick into her wet and moist pussy.

Twilight sat down and watched them have sex while conducting the experiment. Spike slowly started to kiss Starlight while fucking her.
Starlight started to moan and make sexual noises in her breathing from inbetween kisses.
Spike's dick thrusts got more faster and a lot more harder while Starlight's moans turned to screams of sexual pleasure as Spike held Starlight Glimmer real close to his chest.
He started to twitch, grunt, and breathe really hard because his climax was at hand!
Spike's dick thrusts and his breathing got much more faster and was growing more violent.
After a few seconds of that, Spike pre-cummed into Starlight's wet and magical pink pussy only to hear her scream out in sexual pleasure.

Twilight leaned in anticipation. Then suddenly, Starlight's body absorbed Spike's Pre-cum shot and traveled through her body and went to her breasts.
Starlight felt a tingling feeling in her DD sized breasts and was flustered by the tingling sensation that was happening inside her tits.
Spike had closed his eyes throughout the sexual engagement and was unaware as to what was happening to Starlight Glimmer's breasts.

Starlight looked down at her tits,still flustered as to what she was seeing.
Her breasts started to slowly grow, filling the inside of her milk glands with extra breastmilk and stretching her Rarity cosplay outfit.

Starlight continued to watch her breasts grow from a DD to a DDD. Starlight let a soft squeal escape her mouth as the growing had stopped, making her now DD sized hooters much more bouncable now and made her nipple indention in her bra and the outfit much more visible now.

Starlight was flustered again but this time her ass was growing now! Her outfit started to groan and stretch under the pressure of her growing ass.

Starlight started to say to herself "Whatever you do Spike, please don't cum, just hold it in"

Spike got even more violent with his dick thrusts and his breathing as Starlight started screaming again. Spike held a huge deep breath in as his climax was near!
Then he released his white, sticky, and warm seed from his shaft into Starlight Glimmer making her sing soprano.

Starlight Glimmer got up from on top of the table and jumped down in front of Twilight.
Starlight was hit with another surge of tingling and she stood there moaning as Twilight watched as Starlight's boobs grew 3 bra sizes bigger!
Starlight grabbed her growing rear trying to stop it from growing any bigger.

Starlight gasped in horror when she heard her panties and outfit rip, revealing her huge and jiggling ass!
Her ass was so heavy that she fell onto her fat ass letting out a panicked scream.
Twilight stood there laughing at Starlight being grounded by her own ass! Twilight knew the test was a success!
But the ultimate test was on her. But where was she going to find a stallion that late at night. She had the perfect idea! She could use Doctor Hooves!
This cant possibly end well for him.
*Continues in Chapter 2- Doc Hooves? Twilight goes amazon.*