>"Yes sister, right there!"
>Princess Celestia arches her back-
>"clop clop clop! Anypony home?"
>absolute silence
>The door is opened by yellow magic and a voice calls forth from the dark
>"Twilight, my faithful student, what have I told you about going into our private bedchambers?"
>"You told me to knock, so I did. It's been over a day since I've seen my friendship student Starlight, and no pupil of mine is tardy for their lessons!"
>Another voice joins the room
>"We see. Tis most unfortunate, Twilight. Doth thou seeketh thine pupil posthaste?"
>"Princess Luna? What are you doing in Celestia's bedchambers? And what's that smell?"
>Twilight lights the room with her horn magic aura
>"Ah!"
>Both voices cry out in harmony as the two princesses pull the covers over themselves
>"Why do you two have makeup all over your faces?"
>"Twilight, please afford your princesses some...privacy."
>"Well, privacy or not, I can't find my student! Her magic signature is completely gone!"
>Celestia peeks her head out of the covers
>"Twilight, my star pupil, do you mean to say that you fear something has happened to Starlight Glimmer?"
>"Yes! and it's about to get a whole hay of a lot worse if she doesn't complete her friendship lesson today!"
>"I see. Allow me to- Twilight. Have you checked her house?"
>"No."
>"How could you ask for our aid to find her before checking her house?"
>"Thine student is a blithering fool, Tia."
>"Luna, how dare you! You! You-"
>Celestia aggressively plants kisses on Luna's lips
>"Mmhh! Smooch! Mhm!"
>"Uh, Princess Celestia?"
>"Go now, Twilight. I trust in your judgement to ask for our help. Our aid will be given after royal punishment is given for-"
>"smack!"
>"Ah!"
>"-insubordination."
>Twilight gallops off into the night through the royal castle
>"I thought I remembered seeing rarity wear that kind of sultry makup before..."
>It is a dark and stormy night in equestria
>Twilight thought of a punishment as she teleported off of the castle balcony to Starlight's house
>"clop clop clop! Starlight? Are you in there?"
>"Mfhh! Rmmff!"
>Twilight rears back and breaks down the door 
>"Where are you Starlight! What?"
>Twilight cannot believe her eyes
>Before Twilight is Trixie in the living room, savagely fucking filly Glimmer bound in a rear spreader bar, ball gag, and latex
>"What the hay is going on here? Is that you, Glimmer? And Trixie? You have a penis?"
>"Well, well, well. If it isn't Twilight Sparkle! So kind of you to join us... Take it you slut!"
>"splap! splop! splap! mffrgh!"
>Twilight rips out the ball gag from Glimmer's snoot with her magic
>"I've come to save you!"
>"Twih!...Ligh!... Don't ahhh! Don't sto-o-o-p this. Oh! I di-i-i-i-d this to ah! myself..."
>Twilight's eyes furrow in rage
>"So you willingly missed your friendship lesson?"
>Trixie looks towards Twilight
>"Yes, Glimmer here ah! Won't be having ooh, so tight! Any more friendship lessons ahh! Anytime soon."
>"shlop! splop! shlop!"
>"Twili-i-i-ight! You have to go-o-o-o! It's almost too la-a-a-ate!"
>Glimmer grabs the ball gag and puts it back into her mouth
>The darkness of night in the room is suddenly broken by a magical aura enveloping Trixie
>The light shines outwards from the windows as if the aurora borealis was located entirely in the living room
>Trixie's horn lengthens and sharpens, and powerful wings sprout outwards from her back
>"Yes! Trixie can feel her Power rising! It's overflowing!"
>Glimmer's rear legs are lifted up from Trixie rising off of the ground
>"Trixie will truly be the Greatest and most Powerful!"
>Twilight looks on in utter shock
>"Trixie..."
>Trixie grows in size, her proportions becoming more slender and horselike
>The aura dissipates and Trixie glides gently towards the ground, wings outstretched
>"How do you like Trixie's new wings, Twilight? All Trixie had to do was not cum for a whole day. Only a fool would bow down to Celestia for power."
>Twilight crouches down, snoofing and pawing at the ground
>"And now for my last trick!"
>Trixie shoves her larger, longer cock as far as it will go inside Glimmer's stretchy horse pussy
>"Ta-da-ah! It's gone! Oh! Trixie is-"
>Trixie's newly sized enhanced cock flares inside of Glimmer, locking it against her cervix
>"Aaaaah!"
>Trixie and Glimmer moan together in ecstasy as Trixie's pre and cum are pumped into Glimmer's filly womb
>"sqk! sqrrk! sqik! squrrrrk! squrrk!"
>Each shot becomes slower and more viscous than the last as Trixie drains herself into Glimmer's sex
>"Oh sweet Celestia! Yes!"
>Glimmer's abdomen distends down almost touching the floor
>Glimmer winks desperately around the massive horse cock, squirting slimy filly jizz onto the floor
>"mmfhhh! MMMfhh!"
>Twilight starts leaking at the sight
>"T-Trixie, I will not let you defy the equestrian matriarchy with your forbidden alicorn magic! Prepare to draw your last breath!"
>"Muhahaha-aaaah! It's too late Twilight! Trixie is Greater and Powerfuller than even a fledgling alicorn such as yourself!"
>"The magic of friendship is the strongest magic there is! It won't be undone by your cheap tricks!"
>Trixie turns towards twilight, sliding out of Glimmer while still leaking
>"Never call Trixie's acts a cheap trick!"
>Glimmer spouts a small cum fountain onto the floor and her belly shrinks down a bit
>"Trixie will show you true terror, Sparkle! This will be our last magic duel!"