Okay, now maybe it's time for Arbmos to have some things done for him in exchange for what he could give to Derpy... whether it would be good or bad, perhaps? Well, we'll see how it all unfolds...

Derpy had been at her house until the dusk hours of the day, binging on her favorite muffins, lemon surprise, which she felt in the mood for baking after her little success with her coworkers.

"Now, Derpy, I must ask you for a favor... as part of the exchange of my knowledge to give you." Arbmos said.

"Sure." Derpy said. "What do you need me to do?"

"After nightfall, I will need you to go to the Canterlot Archives, and take some of the books in the restricted wing." Arbmos instructed.

"The Canterlot Archives?" Derpy asked. "But they don't allow anypony in there other than Princess Celestia and her students! How can I do that?"

"Do not fret, my dear." Arbmos said. "Like I said before, my magic shall come of use to you should the situation be too much for you. Complete this task, and I shall transfer a portion of my knowledge of magic into your memory so that you can use it of your own will, rather than relying on me."

Derpy was a bit hesitant; if she willingly did what Arbmos was asking, she could end up getting caught and in a lot of trouble... but if she didn't, then Arbmos wouldn't help her out with her problems. Even then, when compared to dealing with ponies who hated her simply for who she was... the Canterlot guards catching her didn't seem so bad. And if there was little chance of it even happening...

"Okay... but will you be able to make it so I won't get caught?" Derpy asked.

"Absolutely..." Arbmos responded. "...modern Equestrian security, as I have seen in my spiritual projections, is very flawed and imperfect. I myself could slip past the guards in my sleep. As for the books... I need the Book of Unity, the Book of Influence, and the Book of Superiority."

"Unity... Influence... and Superiority..." Derpy repeated just to remember. "...okay, got it!"

"And now... it is time to go." Arbmos said before the horn started to glow red.

After a moment, accompanied by a blinding strobe, Derpy found herself just outside of the Canterlot Archives building.

"Woah, that was crazy!" Derpy said. "What happened?"

"A regular teleportation spell." Arbmos said. "Now, go and fetch me those books I requested. I shall help you should you encounter any guards who interfere."

"Okay!" Derpy said.

With that, she headed inside the the building through an open window. Walking down the hallway, Derpy saw no guards as of yet.

"So... you said they're in the restricted wing, Arbmos?" Derpy asked quietly.

"That is correct, my dear." Arbmos said.

So Derpy set out to locate where the restricted wing was. She happened upon a map on the wall, and saw that it happened to be the second room down the hall from where she currently was.

Once she made it to the room, Derpy began to examine the aisles, starting with "I", which she would follow with "S", and then "U".

"Hm, let's see..." Derpy muttered under her breath. "...Influence... Influence... where's Influence?"

After looking around for a bit...

"Ah, found it!" Derpy said.

Derpy levitated the tome out of its place on the shelf, and held it in front of her with her magic. With a red flash, the book disappeared.

"Woah!" Derpy said. "What was that? Did it just explode?"

"No, Derpy." Arbmos said. "I have simply materialized it in the realm within my horn in which I currently dwell. I shall do the same for the other books upon your discovery of them."

"Oh, okay." Derpy said. "At least I won't have to carry them."

Derpy continued to search for the books she needed to get for Arbmos. She found the Book of Superiority after searching for a bit. Now came the Book of Unity. Derpy looked in the "U" section of the restricted wing, and found the general area that it should be in. She was tapping the books while looking at the titles on the spines, but accidentally knocked a book over as she tried to pry the Book of Unity out from it's place.

The dropped book made a loud hum and emitted a bright light. Quickly, Derpy closed the book, and saw the title as the "Book of Unearthing".

"Who's there!?" Came a voice at the front of the wing.

Derpy's pulse quickened, and she looked over the bookcase to see a lantern light drawing near. The book had indeed unearthed Derpy's presence.

"Ngh... guards coming! Guards coming!" Derpy murmured.

"Panicking shall do you no good, Derpy." Arbmos said. "You need not worry so long as I can still help you..."

Immediately after a flash of red light, Derpy noticed her vision had a violet sort of haze.

"What did you do?" Derpy whispered.

"You are now invisible, my dear." Arbmos responded.

"Invisible...?" Derpy asked, holding up her hoof to see that she was translucent with a purplish glow around her. "...But why can I still see myself?"

"Invisible beings are capable of seeing themselves. It will be up to you, however, to maintain silence, as it is something that invisibility spells cannot grant you." Arbmos said.

With that, Derpy flapped her wings as quietly as she could in order to hover up to the high ceiling. She saw a Unicorn guard patrolling through the aisles below her.

"I know you're here! Nopony can hide from the Canterlot Royal Guard!" the Unicorn said as he scanned through the empty bookcase cavities.

Derpy slowly and carefully tried to fly back down to the entrance to the Archives without the guard hearing anything.

"Show yourself right now!" the guard demanded. "If you wait for me to find you, you'll be in even worse trouble!"

Quickly, Derpy rushed back out the door, and found her way back outside without any guards noticing her.

Arbmos promptly teleported Derpy right back to her house, and restored her visibility.

Excellent, Derpy. Arbmos thought to himself. I knew you could do it through my power... and now that I have these books, it's only a matter of time before I have my second chance to finish what I started...

(XXXX)

Twilight was up into the light hours of the night, racking her brain and searching through every book she had in her castle's library that seemed most relevant. She set up a chalkboard with big letters in the middle spelling "ARBMOS", along with several lines stemming from it to cross-off or scribbled-out notes.

"Arbmos... Arbmos..." Twilight absently muttered. "...grr, I can't find anything on any Arbmos! I guess Derpy was just hallucinating or dreaming or something..."

Spike came into the room in his pajamas and holding a lit candle. "Ugh... Twilight, would you just go to sleep already?" he asked.

"I can't, Spike!" Twilight said. "Either Derpy's going crazy... or she's discovered a new spirit altogether! I have to rule out any possibilities!"

Spike facepalmed. "Seriously, Twilight. Just try and sleep on it. Is Ditzy really that big of a concern that you have to throw away several hours of your life that you could be spending on solving friendship problems?" he insisted.

Twilight sighed. "...Fine. I'll just stop for tonight." she said.

Spike climbed onto Twilight's back, and she began walking to the staircase back up to her bedroom... and of course, Spike fell asleep on the way, leaning his face against the back of her neck.

Still, 'Arbmos'... Twilight thought. ...when I was looking at that name on the board, I just couldn't help thinking that something about it was familiar. I just can't put my hoof on it...

Well, such a discovery might come as a rude awakening, Twilight. Anyways, hope you all enjoyed this chapter, and so we'll see how Arbmos' plans continue to unfold as time goes on... and where they could lead. So, catch you all later! Keep holding on...