Of course she can stay.

Trixie clopped her hooves excitedly. "Ha, Trixie told you."

Luna snorted softly. "We cannot--"

About that. They were there to talk. There weren't any rules about you talking to some ponies if they wanted to talk.

Luna took half a step back. "N-no... I suppose not."

Besides that, why are you creeping around, Luna?

She flushed just faintly. "We have had... incidents. Though your stay with us has been peaceful, by and large, we are obliged to work to ensure it remains as such."

Starlight stepped between Trixie and Luna. "By throwing out a good mare?" Luna was about to speak but Starlight cut her off, apparently emboldened by your support. "She's saved Equestria more times in the last century than you have, Your Highness. And threatened the world less times."

Luna's jaw tensed at the accusation, true or not as it was. "The Stud has spoken. Trixie Lulamoon, you are permitted to stay." She gave Trixie a bit of a glare. "Do not make us regret this allowance."

Trixie waved off the accusation. "The Great and Powerful Trixie will only harm the stud's sense of scale as he is bedazzled by what she has to offer." She grinned at you, happy and smiling. "Now, shall we begin?"

Luna took a slow step back. "Call if we are needed."

You would, but you didn't want the door being banged down before then unless you were being murdered or something.

She was gone.

Starlight let out a loud sigh of relief. "I was worried a moment that wouldn't work. You have my thanks." She saluted lightly. "Now... what price is there for this help?"

You wouldn't put it quite like that. As it turned out, you liked Trixie, as a pony.

Trixie beamed at the praise.

That didn't mean you didn't have some questions! To start, you wanted to hear Starlight's story.

Trixie hopped up onto your bed. "What a Large and Soft bed you have, human."

You told her your name.

"What a curious title." She glanced towards Starlight. "Related, you say?"

Starlight put a hoof behind her head. "Yes, well... It's a long story."

You sat down on the bed and flopped. You had time, and you didn't plan on moving just yet.

"Very well. If you know of my adventures, you know how I... came to be involved with Twilight, do you not?" She sounded a little nervous.

You did know that. She went back in time and it was a pretty good episode, even if your reform was a bit rushed.

Starlight blinked at that. "Rushed? I... I had to witness hundreds, neigh, thousands of worlds torn asunder in different ways by my actions. I kept thinking to myself that she couldn't be that important. That her friends couldn't be so important. I desperately hopped from universe to universe, trying to find one that wasn't a miserable pile on some level or another. The ones with no ponies became almost a relief, a chance to rest... Twilight was there with me, trying to fix it. By the end we had bonded through that misery. It was awful, and I was the one that caused it."

Trixie threw a leg over Starlight, hugging her close and rocking her a little. "Starlight is still sensitive about that. You should be more gentle with her. The Great and Powerful Trixie tries to rise above such pettiness, but not everypony can be as grand as her."

That threw a curve in things. Reality really had been summarized to fit in a telvision show. That made sense, in a way. You apologized for making light of Starlight's struggle. So how did that relate to your home world?

Starlight perked up. "Oh, yes, well... After that trial... one can't help but learn a little about the workings of time and probability." She rubbed at a cheek with a hoof. "I swore I'd never interfere with either again, but then the announcement was made. Most ponies became mildly anxious, but I knew what was said. We would die without foals, and then Equestria would be gone." She narrowed her eyes at you. "You do know who's fault this is, right?"

Celestia took the blame.

"Did she say how?"

She wanted to make the country more peaceful and harmonious.

Starlight nodded. "She did, and she did it by binding everyone to harmony." She pointed back at her cutie mark. "I was right to despise them, even if my reasoning was entirely wrong."

Wait wait wait! How did a cutie mark make mares barren or stallions sterile?

Trixie sat up. "She knows this one. With every passing generation, ponykind was brought closer to the peaceful, boring, infertile middle line. Mares became less... mare. Stallions became less stallion. Both sides weakened into a tepid pudding-like state, and here we are."

Starlight perked an ear at the explanation. "That's keeping it simple, but basically correct. Our kind, ponies, are so chained to fate that we are becoming little more than vessels for its will, and it cares little for reproduction, save for the scant few that 'luck' out and get that as a cutie mark."

Wait, there are those?

"Indeed." Starlight nodded quickly. "They've become something of celebrities, and have lost any hope of leading a life that doesn't involve making ponies. It's a terrible fate that I wish on nopony." She cocked a brow. "I say that, but you aren't much different. Stud, they call you, and for good reason."

That was all interesting, and good to know, but weren't they working towards your home world?

"Ah, yes, it's related." She tapped her hooves together. "I began to explore as the situation became clear. I looked left and right, in other probabilities, but they were all wrong, all of them. There was no hope in rolling the dice and hoping for a miracle. So, I had a new thought... What if we looked back?"

Back?

"To the past," explained Starlight. "Back before Celestia cursed us with... these!" She glared at her mark before looking back at you. "So I began to push. Getting back further than a hoof full of years? A challenge. To breach a century, a true task. But once I was past those? It was like I had broken some limit, and I fell. I wasn't sure how far back I had gone, but I found it... A world without ponies. A world with bipeds, cities, cars, smoke, and technology. These people were free of destiny's cruel grip. These people were vital and healthy. I crept up on one and took him home, to Equestria, to the modern day."

And... the stud program began?

"Exactly so. Using that human's mind, they learned to find others through the shared dreams of all ponies." She pointed at you. "I'm certain you've been told before, but you are a pony. Specifically, you're our ancestor. We are your descendants. Humanity becomes us, somewhen. I couldn't say what inspired them to do so, but... the proof is there."

Wait, was that why you couldn't go home? And that was quite a big statement. So, what, evolution?

Starlight cocked a brow. "I very much doubt that. But yes, going backwards in time causes far more damage than forward. When you go forwards, you simply vanish. There is no real interference. When you go backward..."

Trixie snickered. "She would like to know how that would work. What natural force would push you, human, to walk on all fours and grow hooves?"

This was getting to be a bit much. So... what was it?

Starlight shrugged. "I don't know. I went back to your prime. I would have to search harder, hoping for the best, to land somewhere just as humanity was changing, be it peacefully or in some disaster. I could end up very dead depending on what it is, so I decided to leave that one alone. Do you understand?"

You... kinda did?

Trixie nodded. "Then we have an understanding, and you have the explanation you wanted. You will service Trixie now."

Not so fast! You had a favor to call in first.

Trixie blinked at you. "Is our company not sufficient?"

It was a start, but you really did want to learn magic.

Starlight's suspicious face brightened. "Oh, is that all? How far have you gotten?"

Trixie held up a hoof, sparkling motes of light streaming from it. "Can you do this?"

You explained that you had just started the day before with a basic light spell and you had to practice that.

Trixie snorted. "You are a little foal. It's adorable." She reached up to pat you on the head and stroked through your hair. "Rest easy, Trixie will rear you properly."

Starlight burst into a fit of laughter. "He's no foal, Trixie. He's an adult just like you or I, just horribly confused. Look, don't worry. You want us to help? You got it. Just promise me one thing." She pointed back at her cutie mark. "Help me get rid of these."

That was a big promise to make. You offered to look into it and take whatever action saved ponykind.

Starlight raised a brow. "And if that means destroying them?"

If that was the only way, you'd have to do it, promise or not.

Starlight nodded. "I... suppose I can accept that. You are mature in your thinking." She hopped up beside you on the bed. "I'm sorry if we ruined your sleep."

About that... You were still kind of beat. Would they mind?

Trixie curled up on your bed. "Trixie finds your bed acceptable."

Starlight smirked at her friend before she nodded at you. "If you don't mind? Let's get some shut-eye and we can talk about this later."

You were stuck with them. At least they were letting you go back to sleep, which is what you went to do, mind full of time travel and humans becoming ponies, somehow.

You felt a warm presence and found Starlight had snuggled up against your front. She didn't try to kiss, lick, or otherwise advance, but she pressed in close. A moment later warmth pressed to your back. You were pinned between them.

There were worse ways to sleep.

Author's Note

https://www.surveymonkey.com/results/SM-LYSHLL6N/

The thought of booting Trixie is barely a thing, but you have sooo many questions, starting with Luna.

And bombs are dropped, possibly literally?

Well, shoot... now what?

1) We need to find out how humans became ponies.
2) Let's focus on being healthy for the moment.
3) Are cutie marks really the root of the problem?
4) Sleep gotten, a snack obtained, time to show Trixie who's really Great and Powerful.
5) Let's focus on getting that magic down. You have four willing mentors!
6) This is too heavy. You're not here to handle this. Let's breed more and stop worrying about this... stuff.
7) Maybe it's time to confront Celestia again with this new knowledge.
8) You want your room back to yourself! Out ye vile mares.

Two updates? Two updates. The last one was short. This one is more like it. Put together, a busy day. I've dropped major bombs. Like it, hate it? Let me know among your votes. A vote for 6 is a vote to forget all this extra stuff and focus on the clop, but I think my readers (That's you!) are more curious souls than that. Care to explore further? I eagerly await your votes.