Pillow talk with a Princess.

After filling Celestia's mouth and ass, experiencing in total four bed-flooding orgasms back-to-back leaving Celestia a cum-bloated, fucked-silly mess beside him, Isaac was feeling exhausted and sore. Even with superhuman stamina and staying power, turned out that having a giant cock pumping massive amounts of cum put quite the strain on the human body, and that was before the mind-blanking pleasure that the human mind was not quite prepared to receive. This was going to need fixing, he realized.

As the two of them panted for breath in the vast, empty throne room, Isaac rolled over and buried his mouth in one of the cushions on the royal 'meeting bed.' Muffled by the soft fabric, he muttered, "Are my body and mind rapidly adjusting to having a huge, growing cock and balls, and are quickly becoming able to handle **** amounts of pleasure with ease without dampening the sensations? Am I gradually getting healthier overall the longer I stay in this world?"

"Mmm... Did you say something?" Celestia murmured quietly, eyes still closed as she relished the sensation of being absolutely stuffed with cum in her stomach, womb, and ass.

Isaac rolled back over, feeling much less sore and more awake already. "Nah, nothing." He glanced down at himself, and noted that his body was looking a lot less flabby, though he still had a bit of a gut. He wondered if, rather than becoming some classical muscular adonis, he'd end up with more of a 'musclegut' physique if he stayed in this world long enough. Not that he was planning to leave anytime soon, of course!

Celestia groaned and rubbed her belly, her expression placid and drained. "Ahhh... I don't think I've cum so much... ever. As much as I hate to admit it and leave you hanging, Isaac... I think I'm tapped out." She started to laugh. "You tuckered out a demigoddess and still have energy left over! There's no question you're Harem Master material now, hmhm!"

Now that was a compliment that Isaac couldn't help but grin at. Indeed, his cock was a bit wilted now, but he still felt ready to go at least a couple more rounds. "Yeah, I'm definitely going to need multiple partners to keep this beast down."

"Too bad Luna doesn't wake up for a few more hours..." Celestia said thoughtfully with a wistful sigh. "I could call in some of the servants working today, but I think it'd be best if we built up the core of your harem with ponies you know and have a connection with before opening things up to the general public. There's such a thing as expanding the harem too fast, especially starting out."

"Sounds like you have a detailed plan for this," Isaac said, being careful not to phrase it like a question... before realizing he had little reason not to. "Do you have a foolproof plan for making me the Harem Master of the entire world?"

Celestia opened one eye and winked at him. "Spoilers~... But regardless of my schemes, Canterlot wasn't built in a single day, and neither will your harem. Taking it slow and organically is the best way to ensure the long-term health of your harem."

"What... are the risks involved if we don't?" Isaac asked very carefully, making sure his question was ambiguous.

"Burning you out, for one thing," Celestia replied candidly. "As suitable as you are for being our Master, you don't have any experience being such yet. And no matter how much you or we may want it, going from one mare to a million mares will have an effect on your heart and mind. The last thing we want is for this whole arrangement to become meaningless if you become jaded, overwhelmed, or even bored." She turned her head and gave him a sweet smile. "Besides, you're a cute, sweet guy, and I want you to enjoy this for years and years and years to come. I hope that you will enjoy our company, too."

Isaac was slightly disappointed, but he also had to respect Celestia's reasoning. It was... also kind of nice that someone was looking out for his emotions, even for pragmatic reasons. Somehow, he hadn't perverted this reality so severely that there was no room for emotional connection... even if it was completely stacked in his favor.

With another wistful sigh, Celestia continued, "The other thing is that, well, Equestria has its share of enemies. Villains and villainesses that might see the rise of the Harem Master as an opportunity to advance their own ends. They might attempt to foalnap you or your slaves for leverage, or they might try to control you outright, or they may just see you as a threat to their power and destroy you. That's the worst-case scenario, of course, but we've been let down by a lack of vigilance before."

Oh. Yeah. He'd heard about that, how this magical world had magical supervillains. That would probably be a problem. "Sure, but... Even the villains and villainesses of the world, and other world leaders, crave submitting to a Harem Master above all else, right?"

"Hey, Pharynx."

"...What, Thorax?"

The eldest of the brotherly Princes of the Changeling Kingdom looked over at his younger brother, who was posing with one foot on the throne to show off his massive femboy ass.

"Do you think, when the Harem Master arrives and claims us, that he'll like big butts or... really big butts?" Thorax asked cutely, blushing sheepishly. To emphasize his point, an aura of pastel flame bloomed on his lower body, and his hips and ass swelled to nearly half-again their ridiculously huge starting size, becoming a pair of green pillows that could probably swallow up a leg between them.

The older insectoid-equine anthro, with his dark cyan chitin scales covering his intimidating musculature, folded his arms beneath his imposing pectorals and looked away from his brother's (admittedly enticing) booty. "I've told you before, I don't think it'll be that simple. The Harem Master is going to want a wide variety, and above all, servants who can attend to his every need and dedicate themselves to his pleasure. Slaves who can use every inch of their body to make him happy, no matter what mood strikes him on any given day." His biceps flexed and his big, firm pecs bounced instinctively. Then Pharynx heard giggling from his younger brother, and he gave Thorax his best angry glare. "What's so funny?"

Prince Thorax finished chortling, his large antlers framing his unnaturally beautiful, smiling face. "I knew that would cheer you up. Talking about serving the Master always brings out a certain passion in you."

Pharynx scoffed and looked away, though he couldn't stop himself from smirking. "I'm just dedicated to my work."

"Indeed, we're all in this together. If only some of them would realize that..." Celestia replied with a mournful shake of her head. "Sometimes their desire for a Master gets twisted into something dangerous, or they live in denial and try to **** their power to become the ruler of the world themselves... Thankfully we've had the Elements of Harmony to deal with some of the biggest threats, and some of our enemies have been redeemed and brought into the fold like Eris. But others, like former changeling queen Chrysalis, are still at large."

That gave Isaac a particularly naughty idea. "Huh. That's the official story, but I heard some rumors on my way here... Is it true that you subdued and captured Queen Chrysalis a while ago and have been secretly holding her in the castle dungeon?"

Celestia snapped her head towards him with a small amount of alarm. "Where did you hear that?"

Isaac put up his hands defensively. "Just rumors! I heard some fancy ponies gossiping while I was walking up the main road." That was a total lie, though he had seen plenty of fancy ponies gossiping on his way here - but they were talking more about fashion and boring palace intrigue than anything.

The alicorn shook her head. "I'll need to have a talk with my guards and servants about loose lips... But yes, we've been holding Chrysalis here under heavy security. Not that any of that should concern you."

"Well, I was just thinking... Since I'm the prospective Harem Master and all now... Would now be a good time to see if I can convince a villainess to give up her evil ways with the power of my cock?"

Even though the answer was preordained, Celestia didn't reply immediately, looking at Isaac and then off into the middle distance back and forth in deep thought, no doubt considering every possibility and angle of the problem.

Then, slowly, a naughty smirk grew on her lips. "You know what? You might be right~...!"