Moon and sun, two pieces of the sky.
I see sun 9 times, see moon 7 times.
Books call moments where sun or moon out day and night, reseptically, no, wrong word, ree...spek...tif...lee… good enough.

Celestial say I be here one weak, why one weak? Isn’t Plunder strong?

Need book… ooooh, full day-night called 1 day, 7 day make weak… spelled week… Plunder get smarterer every day!

Wait… Plunder don’t think that sounded right… well whatever…

Celestial be very nice to me, help me learn things, like how to talk and what words mean.

Plunder no talk like pony, no have mouth, I talk with magic! Plunder get thorns, put energy, mana, in them, then think really hard about what I want say to pony or ponies.

Oh! Here she comes now!

“Hello Plunder, have you been doing okay while I was gone?”

Yes! Plunder do very good, me read more books and rest by window… sun so warm and nice.

“Well I’m glad you enjoy it.” Celestial giggled, then Lunar appears, not, I smell her before she walk in, she being sneaky looky pony… what was that word again?

“Sister? Are you well?” the blue Alligator replied… wait, wrong word… Alicorn! She Alicorn! Alligator big lizard that breathes fire!

“Oh yes, I was just having a conversation with Plunder here.”

“Sister… that is a plant, a Plunder Vine even, why doth thou continue this fantasy!?”

“I do not fantasize, Luna! Plunder is different, he’s been learning and understanding! He’s even been able to communicate telepathically.”

“Minotaur Manure!”

“TIS NOT A LIE AND WE SHALT PROVE IT! COME HITHER AND SIT BESIDE ME!”

“Sister.”

“NOW!” Lunar Alicorn makes squeaky noise like mouse before listening to Celestial, then stares at me.

...Plunder feels uncomfortable, should Plunder be doing something?

“Go ahead Plunder,” Celestial speaks up, seeing Plunder’s distress… since when did Plunder start talking in third person?

Focus! Oh right! Say something to Lunar… well, Celestial teach Plunder to be honest.

Plunder think the squeaky sound Lunar pony made was cute!

“WHAT IN TARTARUS!?” ow… Plunder’s poor not-real ears… Lunar pony is loud…

“Ow…” oh! Celestial agrees! “Luna, please don’t use the Royal Canterlot Voice, we’re inside.”
“Oh, right, sorry sister, it is just very shocking to see a plant, something that has no brain and merely has the process of grow, pollinate and disperse, can be intelligent enough to speak!”
Plunder, the ‘no brain’ plant, can also hear.

...Lunar pony got cuter, she put hooves to face while face go red… Celestial called it ‘blushing’.

“I know, we are sorry dear Plunder, I shall take more consideration before speaking my thoughts.”
Thank you… ooh! Plunder learn new trick! I looked at book and found new thing Plunder can do!
“Oh?” the Celestial says. “Please show us what you have learnt.”

Okay Plunder… focus… Plunder make mouth things that shoots spores, like they say in the book. Lunar looks scared. “He hath made sporetraps!? Sister, this is incredibly distressing, if your plant can make these he could do… unspeakable things to us while we’re unconscious!” unspeakable? Like what?

“Luna, I am disappointed in you! Assuming Plunder would violate us with this ability! Why would he show us such a thing then!”
“It wouldn’t matter if he showed us or not! And I know the tales! The traps knocking out vulnerable ponies, then the vines perversely taking their holes for some sick method of pleasure and reproduction!”
I thought it could help Lunar pony…
“Huh?” Lunar says, confused by Plunder’s words.
You always stay up during night, sleep during day, books say ponies should sleep other way around, help you sleep at night!
“We… thank you Plunder, but we do not sleep during the night because that is when we work.”
Ooooh… you night owl!
“Night… Owl?”
Pony who works at night, it common.
“It… is?” she has the happy eyes! Plunder do good.
Well… if you no need sleepies, you need hornies?
“I… what!?” both say, confused.
I can make sleepy spores… jokey spores like poison joke, and horny spores!
“Horny…” Celestia stops herself as she blushes. “Wh-why would we need that!?”
Well… Luna do hoof thing in your room. Luna blushes… hey Plunder getting better! And you mumble about rutting her in sleep. Celestia Blushes.
“B-but-” Celestia starts. “We’re sisters! Doing such is… uncouth!”
“Incest!” Luna says, agreeing with Celestia.
So?

“So!? Look, there is no way we’re agreeing with some plant’s misguided assumptions!” Luna says… if Plunder had a mouth Plunder’d be smiling.
Fine… plan B.
“What are you-”

Plunder sneeze, a big sneeze, a sneeze so big it sent a wave of spores to spread all across Equestria.
Also have changey spores.
When Celestia and Luna get back up, they become bipedals, big minotaur boobies on the chests, hands, and best part...

No possible way to hide naughty bits.

“AIEEEEE!” Celestia scream, covering crotch. “Plunder! Change us back right this instant!”
No.
“YOU-”
Not until you admit your feelings for each other.
“I DO NOT-”
Then no change-backs.
“You… YOU…”
Kill Plunder, and you stuck…

It took ten seconds for Celestia to break.
“Alright fine! I want to fuck Luna! Okay!? I love her more than any mare or stallion in the world and has the hottest plot in Equestria! Happy!?”

“...sister?” oh look, Luna heard.

“L-Luna… I-MMPH?!” haha! She got cut off by kiss! I was right!
“Sister.” Luna says, looking her sister in the eyes. “Plunder’s right, we shouldn’t have hidden it for so long, I love you and wish to be with you in every way, more than sisters, more than Diarchs, I’ve wanted to taste your marehood for so long.”
“Luna this is unprofe-”
“I don’t care!” she goes to her knees and treats Celestia’s front hole like a dog treats a feeding dish… oh hey I’m doing metaphors!

And speaking in first person!

Either way, Celestia caves in and eventually they start going at it in a sixty-nine position.

...should I tell them I was bluffing and this was permanent?

...no I don’t want to be kindling, I’ll just say nothing, maybe they’ll forget I mentioned it or decide to stay anthropomorphic…

...I am so dead…

Author's Note

yep, he learns and he surprises, now this is officially an anthro verse with princest!

...well, almost...