The princess's eyes grow impossibly wide as we traverse the portal; her expression of stupefied awe gives her a vague resemblance to a cow. I know she would not thank me for the comparison, but it's accurate. I can't blame her for her amazement, though; Underhill is a majestic sight to behold.

We step out of the gate onto a wide, sweeping path of white marble, bordered by bushes trimmed with mathematical preciseness into fantastical shapes. The huntsman cradles my mirror against his chest, so I can see everything around us. The unexpected gesture is touching – while I can watch the world from a million different reflections, I prefer the views from my mirrors. The clarity and depth are particularly welcome in a place like this, where everything sparkles with power. Even the cobblestones glow with iridescent light.

"What... we... where are we?" the princess stutters. She reaches out to brush a finger over a bush shaped like a centaur, only to leap back with a yelp when it raises its spear threateningly.

"Underhill," our elven guide tells her, a hint of condescension flavoring his tone. He doesn't bother to warn her about touching things; if she can't figure out the rules of this world, she doesn't deserve to survive.

I consider warning her myself, but she has a modicum of common sense; she keeps her hands to herself after that. I can see her twitch as we pass more leafy statues, which rotate to face us. Dusky emerald, only a few shades away from black, gleams between the branches of their faces where their eyes should be. The sky above us is a perfectly uniform blue from horizon to horizon, with not a single cloud to be seen. There's no sun, either, though there's plenty of light – it streams down from the sky in silent ivory waterfalls, invisible to the mortal eye. That sourceless illumination is the least of the wonders of the fae realm.

The statues that surround us are another 'wonder', though a more macabre one. They guard the path that we walk from hostile intruders, but they are far more than mindless constructs. The spirit of a lesser fae is trapped within each one, bound to the foliage for a term that may stretch years or even decades. Rooted and immobile, they are unable to speak, even to each other; their only diversion comes in the form of visitors like us. It's a wonder they don't go mad – or maybe they do. Would there be any way to tell if they did?

Unfortunately, that is not the kind of question you are encouraged to ask when in the fae realms.

The number of permissible questions is actually distressingly small; the fae do not encourage idle curiosity. For a being like me, it's quite frustrating, for Underhill is one of the greatest sources of mystery in any of the universes I can see. Constantly changing, always in flux, it's a repository of magic and intrigue far beyond that known to mortal-kind. The marvels held within are legion; fae are nearly as hungry for treasure as dragons. I couldn't care less about the baubles, but the libraries alone hold enough information to entrance me for a hundred years. Thousands of tomes on history, magic, artificery, and more, all cloistered away on dusty shelves... the potential knowledge contained within is enormous. Maybe, if I'm lucky, I could even find a book or two on the complexities of the multiverse.

Or maybe not. For the most part, Underhill seems bound to a single universe, though its connection to time is flexible. Each world has its own lords of the Sidhe, who do not – as far as I know – know of each other or speak with each other. If the farseers have more knowledge of the sea of universes, they do not share it. Even they, to the best of my knowledge, are firmly attached to the world in which they reside.

But then there are the places like the Goblin Market, which hold a bizarre variety of creatures from a hundred thousand different worlds. One of my mortals, a century ago, often visited the marketplace to acquire ritual components that she could not find anywhere else; I could discern no pattern to the people with whom she interacted. I recognized some of them from the worlds that I can touch, but I had never seen anything like some of the others. Then there were the ones that resembled the inhabitants of lands I know, but they were subtly changed, as though they hailed from a completely different time. Their level of technology often supported that theory; I saw inventions in that market that I've never seen anywhere else.

I harbor a suspicion that my maker can be found somewhere among those gaudy tents; maybe someday I'll try to find them. Goblin Market is the one place in the multiverse where my powers fail me – I cannot see anything beyond the reflection of my mirror itself. So I would have to convince one of my mortals to accompany me. As the vast majority of them are either unable to traverse Underhill or entirely consumed with their own self-interest, that's not an easy task.

The clatter of hooves distracts me from my thoughts. I pull the fragments of my attention back to my mirror in time to see an armor-clad knight mounted on a snow white elk come to a halt only a few feet away. A coruscating rainbow haloes her lance as she lowers it to point directly at us. The tip comes to a halt only inches away from my mirror, treating me to a close-up of the barbed adamantine point. The huntsman freezes, one hand coming up to protectively cover the base of my mirror.

I switch the bulk of my vision to the reflections on the knight's armor as our guide steps forward and raises his hand. "Peace. They are permitted here." Violet flames bloom around his upraised hand, forming the sigil of a hawk in flight.

The knight nods and lowers her spear. "Proceed." The voice that echoes from behind her helmet rings like a bell; nothing close to mortal sounds like that. I wonder if she's one of the automatons that guards the King's palace? Most elves sound more human, at least when interacting with mortals.

The violet fire dims, and our guide gestures for us to continue towards the crystalline palace that towers in the distance in careless disregard of gravity. Spires rise to dizzying heights, wholly unsupported by anything solid; bridges crisscross the gaps between them. None have anything so mundane as a handrail. The pennants of the King and Queen fly proudly from the tallest tower, snapping in a breeze that exists only around them.

It looks like it should take hours to get there, at least at our pace, but it can't be more than ten minutes before the group stands in front of the filigreed silver gates. Distance is deceiving Underhill – it's one of the things that most mortals love and hate in equal measure about it.

The inside of the palace looks like it was lifted from the pages of a children's storybook. Chandeliers dangle from the ceiling, casting an unnaturally steady glow over the seamless marble floor. Massive windows line the walls, but they don't look out onto the manicured lawn outside. Instead, one window shows a twilight forest, while another opens onto a storm-tossed sea. The one in between those two is pitch black, lit only by the tiny sparks that dart across it every second or so. In one window farther down, I can see a large table laid with dishes for afternoon tea. A trio of brightly-clothed figures – I think one is a rabbit, and another a mouse – is crowded around the far end, while a young girl in a blue dress perches in an overstuffed armchair near the middle.

"Does every window show something different?" the princess whispers, glancing around with a curious mixture of trepidation and excitement.

"I think so, my lady," the huntsman answers in an undertone, when it becomes clear that the elf guiding us won't deign to respond.

Out of curiosity, I try to shift a fragment of my attention into a reflection from a cup of tea, but I bounce back like I've just run into a wall. The shock reverberates throughout the empty spaces between the worlds, dancing along my senses like a thrumming harp string. It feels almost like an echo of the cataclysm earlier, though it's much less painful. Is the window warded against my power somehow? Or does it open onto another world that I'm not permitted to touch? In theory, universes may never touch one another, so I would be surprised if the scene is truly in a different universe. But, in the land of the fae, nothing is certain.

Goblin Market is proof of that.

Our elven guide comes to a halt in front of a massive pair of oak doors, bound in silver. They swing open as he lays a palm on them, revealing a glittering gathering of the lords and ladies of the high court. Most have chosen to assume a semi-mortal form, but I can spot miniature butterfly wings, talons, and feline tails scattered throughout the gathering. A few, whether by choice or necessity, present more inhuman miens – I think I can see a gargoyle in the far corner, and the scarlet-scaled creature beside it could never be mistaken for a mortal.

A fae lady clad in a flowing gown of rose-colored silk sweeps out of the crowd. "My darling, you've survived!" she cries, enfolding the princess in a perfumed hug. The princess immediately bursts into tears and clings to the lady's waist – I assume that this is her fairy godmother. A faint dusting of silver shimmers in her pale hair, proof of her allegiance to the king, but she doesn't wear the mark of his sworn servants. The power wreathing her tastes of smoke and cinnamon, with just a hint of old blood; she's not the benevolent guardian that she pretends to be, I think.

The huntsman turns, and I notice that our guide has slipped away into the crowd. I spot his reflection in a fluted glass of bubbling amber liquid – he's talking to a slender, androgynous figure with a distinctly canine cast to their features. Since he's no longer important, I designate a fraction of my attention to watch him, and turn away.

"Oh, you must come with me to meet the king," the fairy godmother urges, hooking her arm around the princess's elbow. "You too, dear," she adds to the huntsman. He flinches reflexively when she offers him an arm as well, and she giggles. "Oh, where are my manners? You may call me Lily. I am her highness's fairy godmother." She holds out her hand, as though she expects him to kiss it.

He bows, keeping one hand pressed against my mirror, and she withdraws her hand. "Thank you for watching over her, my lady." He doesn't give her his name, which is smart – you never know what the fae can do if they have your name. She certainly didn't give him her real name, though most humans wouldn't know what to do with the true name of a fae if they were handed it on an iron platter.

Lily laughs. It sounds like the tinkling of wind chimes in a gentle breeze. "Oh, it was no trouble. Come along, dears, the king is waiting."

I'm not sure why she's acting like an airhead; the power currents flowing around her don't belong to an imbecile. From what I can see, she's probably one of the strongest members of the court, or at least the ones currently in attendance. Maybe she's trying to put the princess at ease. I get the feeling that this little show is put on for our benefit, since I doubt any of the fae around here believe it.

She leads us through the crowd and the surrounding fae subtly fade backwards to give her – and, by extension, us – space. More than a few of them study us from behind their glasses; I can hear a murmur of speculation rising as we pass. Only a few are uncouth enough to stare openly, but everyone wants to know what a mortal princess is doing in the court.

That's only to be expected. Mortal visitors, here on their own volition, are rare, and they're always a cause for speculation. The courtiers are polite enough to keep their whispers low, so the princess can't hear them, but I can see the way the huntsman tenses at every new glance. His hand is resting protectively on my mirror again. I wonder why – as far as I can tell, none of the comments are directed at me.

"Your majesty, may I present Her Highness, Princess Ardelia of the kingdom Sherwyn?" Lily gestures to the princess, who gracefully sinks into a low curtsy with her head bowed.

"So this is the princess." The assembled court quiet instantly as the deep voice rings out. The huntsman turns my mirror slightly, and I get my first clear look at the King Oberon of this world.

As always, words fail to do him justice. I've seen him, or those who serve in his place, in other universes, and I can never come up with a suitable description. He radiates a kind of sensual power that I can feel even through my mirror, power that allows for nothing but submission. The princess sways slightly as the echo of his words dies away. "Come, girl, you may rise."

The princess manages to resume her feet without incident, but I can see her hands trembling. "It's an honor to meet you, your majesty," she announces into the silence.

Oberon smiles genially. "Your godmother has spoken highly of your beauty and your grace. I am pleased to see that her words are not unfounded." His allure intensifies. "Come closer."