Sunburst's mind was working in overdrive as his body (metaphorically) petrified. The survivalist part of him that usually only reminded him that eating and sleeping were good ideas noted that he had exhausted his magic in a setting that, while his, was still unfamiliar and included a potential predator, so overrode everything else for now and locked his limbs in place. The part of him that loved action stories and often imagined himself doing awesome feats clammed up, not wanting to do anything life-threatening near those massive fangs. His studious side rifled through his memories for more information on changelings, and the best it could come up with were self-admitted legends and hearsay due to how secret the beings were, although almost all the illustrations had those fangs in them. His social side, while having somewhat lopsided development, was able to note that, if the fangs were ignored, the mouth was in a awkward smile he often saw when he was practicing asking ponies out in the mirror in his teen years.

He really wanted to stop focusing on the fangs, but they were eye-catching, especially in an adrenaline rush.

The changeling's smile grew strained as the silence dragged on. Eventually, he broke it with, "I know this won't sound convincing, but I promise I don't mean you any harm."

Ironically, the echoed words did make him feel a little less on edge. "W-what do y-you want with me?" Apparently not enough to keep from stuttering, though.

"Well, I noticed that you were very lonely, which is the only time I've noticed that to any degree since I got here. You're also not from here, so I thought that maybe you needed a friend." The awkward smile grew a little wider.

Sunburst blinked. He was expecting that unusual things might happen around, but a friend request from a changeling was a little out there. It wouldn't be the first time in recent memory that somepony tried to pull a fast one him, so he cautiously replied, "I don't need any friends. So long as I have my studies, I'll be fine on my own."

"Oh. I could use a friend, so-"

The unicorn didn't pay attention to the rest of what the changeling said, instead dealing with an unbidden memory from many years ago. It was a few weeks into his schooling and Celestia's School for Gifted Unicorns. He had gotten a letter from his hometown, the one he was looking forward to reading the most. That was, until he got to it, angry words inked onto tear-stained paper. It took the wind out of his sails for weeks, and the message written between the lines still haunted him.

"I make for a terrible friend!" He blurted it out, interrupting the changeling.

"Uh-"

"Look," the unicorn continued, having calmed down, "I've hurt everypony I've had a connection with. No one deserves it, so for your sake, no."

The changeling sighed but otherwise remained silent. Surprisingly, the ensuing awkward silence lasted for several minutes. It seems he was also somewhat used to them, just like Sunburst, but few were as good as he himself was with them, and lacking the home field advantage, the changeling asked, "Is the offer still open?"

"...What offer?"

"You did say you wanted to help out with the dark magic inside of me. I know you were just talking to a bird, but, well,..." he trailed off, not knowing how to continue.

Sunburst brought a hoof to his chin. While he did want to be left alone again as soon as possible, here was a once in a lifetime opportunity to learn about a species that was mostly in the realms of myth and legends, and lately an endless wellspring for the tabloids.

His curiosity always got the better of him. "I can't promise anything, since very little is known about your kind, but I should be able to learn what's going on and maybe find a way to dispel it."

The changeling thanked him for that. The unicorn sat down on one of the dinner stools, and after being motioned to do so, the other being did so as well.

Since he was beginning to tire of always thinking of the changeling as, well, that, Sunburst asked for a name, and got Thorax as a response. It might've been a pseudonym, but that didn't matter anyway.

Now came the tricky part of diagnosing what the dark magic even was. He didn't know many spells involving dark magic, and even if he wasn't magically exhausted, the one he was using was just about the only one at his level of power. All he could do was ask questions and use his limited knowledge to come to a conclusion.

Over the next hour, Thorax recapped his 'encounter' with Sombra and his dark magic, the effects of it, how it got removed, and also clarified that the hunger was ever present for changelings and that (as far as he knew) he was never exposed to any similar magic before. Sunburst took notes the entire time, and looked them over once the session was finished.

"From what I can tell, the dark magic has been there for as long as you can remember," Sunburst explained. "For all I know, it's fully integrated into your biology, I can't remove something this deep-seated."

Thorax's ear frills drooped, but he didn't bother asking the obvious question.

Sunburst answered it anyway. "I could maybe spot cleanse a small bird's tainted feathers, but removing dark magic takes a similar level of conventional magic to erase an instance of it. If it's always been with you, then your ancestors must have been hit all at once with a massive dark magic attack. To curse an entire species..." he shook his head. "It would take an alicorn to brute force it out, especially when the Crystal Heart couldn't."

Thorax sighed, disappointed, but not surprised. It was not the first time his hopes were dashed, and it would certainly not be the last."

"Still," Sunburst continued, regaining the changeling's attention, "there is another way. Part of dark magic's core is that you take tradeoffs to get extra power." He shifted his eyes across the room, as this was the sort of thing he was not supposed to know. "A very common sacrifice made is durability. Many, many spells have a weaknesses baked in that can cause it to crumble under the right circumstances."

"So what would need to happen for my hunger to vanish?"

The unicorn rubbed the back of his head with a hoof. "That's the tricky part. The original spell would have it, but it would be tricky to find, assuming it had been written down at all. If a spell exists to figure that out, I don't know it. I don't even know a concrete example of this, just something I read in a few books on the subject. In other words, no idea what it would be, and no good idea on how to find it."

The frills drooped again. "I guess that's not surprising. If it were easy, someling would've done it by now." The changeling got up from the stool and said, "Thanks for the help. I didn't get exactly what wanted, but it was great of you to try."

"I'm sure there's somepony that's willing to have a changeling as a friend, though it might be easier if you started off using a disguise."

"I'd rather not. It... just seems like a better idea for there to be no false pretenses and for them to truly like me for who I am."

Sunburst winced slightly. "I fully understand that sentiment. I've felt it myself plenty of times."

Thorax looked awkwardly around the kitchen. "I guess it's a good time for me to leave, then."

"Good luck," the unicorn said as his acquaintance left for the main hall.

A few seconds later, the chitinous head popped back into the room. "Could you please not tell anyone about this? It would be really troublesome for everyone involved if the guards started making changeling sweeps."

He nodded in response. It was too much trouble reporting to the guard and spending time answering their questions was not nearly as appealing as further studies.

After hearing the sound of a changeling transformation and his front door swinging open and shut, he also saw an unfamiliar pegasus fly by his kitchen window into the sky. Since that was almost certainly Thorax, Sunburst was finally alone again, and could let himself relax in full.

Well, that was an experience. At least he learned that the changelings were cursed and a bit driven by their unnatural hunger. There was also the strange fact that the Crystal Heart was perfectly capable of banishing Sombra and his magic, but not the innate corruption of a changeling. He couldn't help but wonder if there are other limits to it, and high as they seem to be.

That settles it, then. He'll go looking for more information about it next. Especially interesting would be the possible insights into magic it could provide as well as possible improvements that could be made thanks to the advances made in the last thousand years.

Author's Note

Sunburst's definitely getting a place in a/the epilogue, if only to tie some loose ends here. I also tried to keep sections that would've amounted to repetition of older parts of the story as short as possible. Dialogue still tends to take up more space than anything else I write, though.