Slayer

The talk with Discord didn't do anything to ease Twilight's unease about the situation. It did leave her exhausted, however, so she decided to sleep for the night, even if it was a bit early.

Of course, just like Aegis said, the moment she was fully asleep, she was subject to a repeat of the visions she saw when she touched The Slayer, albeit less painful. Thankfully, it felt like she didn't have to suffer through it for long before Luna appeared, and managed to somehow pull her out of the worst of it.

"W-what?" Twilight asked, once she got her bearings. "Oh, hi there, Luna. Guess I'm dreaming?"

"That is correct, Twilight." Luna looked behind her, as the visions continued to flash by, now in the distance. "I don't know how many times I've seen them, yet they still make me uncomfortable every time."

"Yeah, it's..." Twilight winced. "It's something. Can you make out anything notable?"

Luna squinted, then shook her head sadly. "I'm afraid not, at least not anything I haven't seen before."

Suddenly, Twilight's eyes widened. "Oh! Discord was able to tell me a bit more about The Slayer today!"

Luna gave her a puzzled look. "Really? I thought he told us all he knew already."

"He told me that he visited Tartarus right after he broke free," she explained. "For some reason, the demons weren't even trying to get out, and they looked afraid when Discord mentioned The Slayer."

Luna looked into the distance, deep in thought. "Even demons fear him... Interesting."

"He did say that's all he could get out of them, though," Twilight finished.

"That is fine. It is still a bit more information than we had. Good work, Twilight."

Suddenly, the void around them started to fade to white.

"Ah, you are waking up," Luna said. "Continue your research, but be careful."

"Okay, Luna. See you later, then!"

Discord didn't sleep at all that night. Instead, he simply remained seated in the recliner, staring off into space. His talk with Twilight made him start thinking about things, and he wasn't entirely sure what to do about it.

Fluttershy was a bit worried, naturally, but it was easy to reassure her and have her go up to bed herself.

By the time the sun started to rise, he had made his decision, and snapped one of his claws. In a flash of light, he was now flying above the Everfree Forest, close to the bottom of a cliff face.

Discord wasted no time and dove to the base of the cliff, and after snaking his way through some trees, he came to a large cavern. Sneaking inside, he found Cerberus in much the same place as usual, sitting in front of the gate while its three heads kept watch.

He didn't even bother to use a distraction, instead just making a beeline for the space above the gates. Cerberus got up and barked furiously, but was unable to do anything in time to actually stop his entry.

The entryway of Tartarus was much the same as he remembered. The closest demons were still a good distance away, and as Discord flew closer, they still backed away, but otherwise ignored him.

This was good, because this time he hoped to go a bit deeper, to get some proper answers.

Twilight awoke peacefully, which was broken when she managed to accidentally roll off her bed. Fortunately, her pride was the only thing that was injured, and she reminded herself that the morning wasn't quite ruined yet.

She was up earlier than everyone else in the castle, which was unsurprising. It did mean that the kitchen was entirely empty, though, so that was a plus. Even still, she wasn't particularly hungry, so she just snacked on half a sandwich that was left in the fridge (no name with it, so it was free game). She also used this time to think over her options.

She could go to Discord again to try and get more out of him, but she had the feeling that he already told her all he knew about The Slayer. Likewise, going back to the princesses' lab wouldn't help much, either. She supposed she could try and visit Tartarus directly, but that seemed like not such a good idea.

It seemed like she had reached a dead end on the subject. The only way to possibly know more involved questioning either the demons of Tartarus themselves, or The Slayer. Obviously the former was out, and the latter would be impossible without letting him free, which was also probably a horrible idea while she still knew so little.

If only Celestia and Luna were able to witness his actions a bit earlier...

As she thought that, an uncomfortable thought wormed its way to the forefront of her mind. She could still use that time travel spell that Starlight tried to use, right...?

Twilight tried to shake the thought off. She had already made her promise several times to never mess with time travel again, so using it herself would only hurt their relationship and make her into a hypocrite.

Then again, she only made Starlight promise to not use that spell to change history. So there shouldn't be anything wrong with just watching, so long as she didn't change anything, right?

But that would be almost impossible. It was a transportation spell, so she'd have to be right there in order to even see anything, and her mere presence would be enough to change the timeline in potentially drastic ways.

Assuming she was actually seen.

No matter how much she tried to rationalize away the idea, her mind kept bringing up one fact. She did have a rather powerful cloaking spell somewhere in her collection, so using that in combination with the time travel spell...

Once she finished the sandwich, she made up her mind, and started heading towards the library.

The deeper Discord went into Tartarus, the more numerous demons became. However, they still remained non-hostile to him the whole time, although at some point a few of them started to watch him as he went by. The rest either continued to mindlessly mill about, or were taking part in some sort of small congregation, usually headed by bigger demons. Some sort of class system?

The landscape slowly began to change, too. Near the gate to Equestria, the area was mostly just arid, red dirt, with a few small lava flows visible in the walls here and there. As he got deeper, not only did the space seem to open up, far more than what should've been possible with the geography outside, but rock formations started to become a regular feature, many of which had markings in their own demonic language. Discord could've probably worked some magic to see what they said, but he didn't particularly care to at the moment.

Eventually, the ground disappeared entirely, and was replaced with a series of massive rock "islands" floating in a sickly yellow void, connected to the land behind him with giant chains, with bits of rock stuck in it here and there. One of the closest islands featured a rock sculpted into the skull of a demon, complete with fire burning eternally in its eyes. Unoriginal, but effective decor.

As he hovered next to the void and looked at the giant skull, Discord heard a voice. It sounded like it was both booming around him, and also inside his head slightly.

"Why are you here, outsider? This is not your realm."

"Yes, I figured that out by now," Discord said back. "Really like what you did with the place, though. It's a classic look, I can appreciate it."

"Enough of your foolishness. Explain yourself, or leave now."

"Fine, fine." Despite the warning, Discord still poofed up a reporter's microphone, holding it out in front of him. "I was wondering if you could answer some questions of mine about a certain someone."

The voice was silent for a brief moment. "Who do you speak of?"

"I feel like you already know who. Perhaps 'The Slayer' rings a bell?"

Even though there were no visible demons in the immediate area, Discord still felt like there were countless eyes staring at him the moment he said it.

"So... It appears you know about The Doom Slayer."

Discord cocked an eyebrow. "Doom Slayer? A bit of an overdramatic title, if you ask me."

"If you knew the true power of The Doom Slayer, you would not jest so lightly."

"Oh? Sounds like he has a history here. Do tell."

And so, the demon recounted the tale of The Doom Slayer, and his eternal quest to vanquish all of Hell. Discord listened intently as he was told about his undying rage, his almost incomprehensible speed and power, and his limitless brutality, all of which was used for the sole purpose of crushing anything and everything demonic, in many, many realms across the multiverse, as well as the deepest pits of Hell itself.

"So let it be known, chaos spirit," the voice finished, "so long as The Doom Slayer remains entombed, we shall not touch your realm, for fear of setting him free once more."

Discord kept himself from letting out a gasp. "So, you know that we have him, then?"

"Indeed, we have been watching your realm for centuries, to ensure that he remains imprisoned. But know this, we are still watching, and we know that one of your kind is dangerously close to letting him escape."

"One of my kind...?" Discord muttered to himself, before his eyes went wide. "Oh dear."

The voice continued. "Should we see that he is being set free, we shall invade your realm again, until he is sealed once more."

Discord didn't offer any response, and instead turned around and started flying as fast as he could. His teleportation wouldn't work until he was at least outside of the gates, back in Equestria.

Hopefully he had enough time to stop Twilight from unknowingly bringing a second Tartarus invasion.