Twilight Sparkle, previous student of Princess Celestia, now current ruler of Equestria, stands within a dark room, only lit up by the magical glow of her horn.

Within the grasp of her magical hold is a sheath of keratin, gray and becoming red at the tip.

This was previously King Sombra's horn. It had broken off when he was banished from the Crystal Empire for a second time.

She'd found it after exploring the Frozen Northern Wastes, looking for anything involving a magical signature.

It pulsed back at her with one, and she had gently wiped the snow away.

This was King Sombra's horn, and it has no rings in it. No spiral at all!

When it comes to unicorns, there are a few different ways for a horn to grow, usually present from birth.

Though, she was told that Celestia and Luna's horns simply changed over the centuries of their rule.

The direction in which a horn spirals is visible from birth. Right, or left.

There are always grooves present on the horn.

An issue was present when she was a filly involving left-spiralling unicorns not being able to cast spells with the same efficiency of magic usage as their right-spiralling compatriots.

Oftentimes, this was why left-spiralling unicorns would drop out from Celestia's School for Gifted Unicorns, one particular example being a young, amber-coloured colt with a white patch on his nose.

Twilight would eventually meet the dropout via Starlight Glimmer, though she didn't share a class with him.

Sometimes, though, there were the anomalies. Sunset Shimmer, last Twilight had checked, was a left-spiralling unicorn.

(Celestia kept a backlog of incident reports involving Sunset Shimmer, and, with mirth adorning her voice like a veil, showed all of them to Twilight, all of them except the final one.)

(Apparently her spells had a chance of backfiring, presumably due to faulty spell matrices and not accounting for her left-spiralling horn...)

(Twilight Sparkle did not have a left-spiralling horn.)

To resolve the issue, Twilight Sparkle, Starlight Glimmer and Sunburst began working on converting an extensive library of spell matrices from being commonly used by right-spiralling unicorns to being able to be used by left-spiralling unicorns.

What mattered now was getting them standardized and approved for use within public education, as well as transporting the books to libraries across the expanses of Equestria.

(That could wait.)

The amount of rings in a unicorn's horn was often thought to correlate with how much magic they could expel in spellwork.

Twilight Sparkle hadn't really seen any evidence of such a thing.

The amount of rings in a unicorn's horn did, however, seem to correlate with how old the unicorn was. Older adults often had more rings, while babies that were merely months old had a singular ring in their spiral that went straight to the tip.

A unicorn like Starswirl the Bearded, or Mistmane, many years her elder, would have more rings on their horns, simply because they were alive for longer, and thus their horns would have grown longer in the time that they'd lived.

The slight curve to Sombra's horn didn't strike her as odd, though. Mistmane, herself, had a curved horn.

(And a flowing mane. Perhaps both Sombra and Mistmane were simply very powerful sorcerors, hence the slight curve to the horn?)

(But Starswirl was also said to be powerful.)

(Starswirl worked more in the theoreticals than the actual spellcasting.)

Luna's horn, she'd said, had initially grown straight, before it started to curve into a shape resembling a crescent, as other changes began to become apparent.

She'd described it as changing with the phases of the moon, pointing to the halo of moons around her, all showing different moon phases.

(Twilight had made sure to note down what phases were currently shown, and, sure enough, they were the next phases in the lunar cycle.)

Celestia's remained straight.

Cadence's had begun to curve. There was one bump on the horn already.

(The current theory is that it would form a heart. Discord made a betting pool on that. She'd contributed five bits.)

Her own stayed ramrod straight.

Although, thinking about it, Twilight Sparkle did wonder. Were curved horns seen as desireable within society? Were they held up as a mark of beauty, of privilege?

She could poll the populace on that. It might have some fairly interesting results.

If Discord was a pony, would his horn grow jagged? He already had a bulbous horn, pointy at the tip, probably from some other ungulate, and a deer antler on his head in his usual form.

She slowly rotated the horn within her magic, ears pricking.

The fracture point likely wasn't a clean cut. Neither was Tempest's.

Undoubtedly, it would have caused Sombra quite a bit of pain if he were still alive after the mass banishment spell, nevermind the unstable magic.

(Wouldn't this just power him up more, thus causing more magical flares, thus giving him more pain in a cycle fit to be called an ouroboros?)

Theoretically, though, because of the magical signature, he could be brought back.

The magical signature she'd detected within the Northern Wastes had come from this horn, and it wasn't a residual one that was left by a spellcaster.

No, this horn was still live with magic, somehow.

After death, the inherent magic that a unicorn has and can channel through the horn, the reserves of magic that remain within them (often overlooked, and said to be a holdover during evolution, similar to the appendix), these magical bits and bobs release all their energy out into the ambient wellspring of magic within the plants, the air, the sky.

Usually it happens within the course of a few weeks. Flesh gets stripped from bone after the body is buried, and it gives the magic a new hole to leak from, thus going back into the soil.

(There was an old legend about unicorns being fallen stars. Twilight never bothered confirming it with Luna, especially when not every unicorn has a star-based name.)

(It may have inspired her mother, though.)

Perhaps buried unicorns from long ago eventually contributed to the growth of some more magical plants. Poison Joke being one of them, though it could have just as easily been one of Discord's more mildly irritating creations.

Or perhaps the ambient magic within the soil, having had a buried unicorn within it, could eventually spread out into other areas, slowly becoming more distilled with time, and perhaps this would cause a much slower change to the plants.

Twilight did not know of any mass graves with the majority containing unicorns.

While it would have been interesting to see the plants that could sprout up from a mass grave of mostly unicorns, the fact that she thought it could be something of interest disturbed her on a particularly visceral level.

(What would her mentor think? What would her brother and sister-in-law think?)

(Would her friends even look at her the same if she told them of this particular thought experiment?)

She shook herself out of her thoughts, and looked at the horn with a mixture of pity and wonder.

She wondered if King Sombra thought about these things too.

Author's Note

i have impostor syndrome and it sucks shit.

i also find the idea of king sombra getting revived by twilight specifically for her wanting to learn dark magic to be incredibly funny.