This is a Diary from a High Elf long ago in the fantasy RPs. He lived during a time when humans were just coming to the Olde World and Elves lived almost completely unopposed in their power. It is currently in the possession of Valen Gray in the New World RP but you can read some excerpts here:
(please excuse any grammar errors)

Introduction

I am writing this even with the general disapproval of my colleagues because I feel that the evil of the Netherworld must be studied in order to defend oneself from it, and to perhaps defeat it someday. Make no mistake, knowledge is the most powerful weapon of all, you must know your enemy if you are to defeat him. I can only hope that I live long enough to see the mortal races freed from this evil.

My research will be done personally, and alone. I will summon demons, imps, and other evil creatures from the Netherworld and bind them in a powerful rune circle passed down by great Elvish Summoners before me. I will then hold them in place as long as I can and use various methods of persuasion to get them to tell me as much of the Netherworld and Demons as possible before they are able to break free from the circle and then I have to banish them back to whence they came. My research will be as dangerous as it sounds and I greatly recommend that it never be copied. I am doing this in the hopes that later generations will never have to.

Day 1

There are many different creatures that inhabit the underworld. The most common are naturally Demons. There are various kinds and no clear lines of distinction. I began my research by summoning a rather pathetic creature, an Imp, on my first test. He was skittish, and afraid as Imps tend to be of powerful spell casters. His name is unpronounceable in mortal tongue so I see no need to write it. We started our session with fairly simple questions. I asked him to describe the Netherworld for me. He seemed puzzled at why I wanted to know and was not compliant at first, but after threatened with Holy Water he became quite forthcoming. He told me that the Netherworld was split up into levels. As believed it is deep underground, in a cavern of sorts, but the ceiling so high that it cannot be seen, even flying to it takes a long time. Great stalactites and stalagmites, some larger than the highest towers, cover the landscape. Inside Demon Lords carve out their palaces.

I now asked him of Demon Lords. He tells me that in the Netherworld there are many Demon Lords serving various Demon gods and goddesses. They each have their own fortress and a small army of lesser Demons under their command. They are always plotting against each other and assassinations are quite commonplace. Usually the murders are for political gain in the eyes of the deity they serve, but often times it is just because they can. Each deity has below them a "First Demon Lord" who runs the deity's affairs of commanding it's servants and carrying out it's wishes. This title is the most coveted of all and is usually obtained by killing the current First Demon Lord. Occasionally a god will appoint it's own First Demon Lord, and in such a case none will oppose them, instead they must wait when the god becomes displeased and kills the First Demon off, allowing a power vacuum for a new First Demon.

We returned to the subject of the Netherworld landscape. The Imp told me that the ground was covered in rocks and dirt and no life grew anywhere. The only light in this realm comes from volcanoes and enormous pits of hot magma. The volcanoes never sleep and are always spewing forth rivers of molten lava. In the upper "sky" regions of this realm are many floating rock platforms. A great field of them is high up, almost three quarters of the way to the ceiling. Flying creatures inhabit this region, and occasionally come down to feed upon lesser Demons.

As the Imp continued to describe this place it seems that Demons are just as evil to each other as they are to everything else. This is much to my surprise as it has always been believed they are a unified force.

Finally I asked the Imp of the various creatures in the Netherworld and their ranks in their society. The highest up are naturally the Demon Lords who run various affairs. Then below them it seems to be survival of the fittest. There are Succubi, beautiful temptresses, all female. They come to the land of the living to mate with men and then give birth to Demon Spawn. Demon Spawn are horrid monsters, neither man nor demon. They are sometimes simply let loose on the mortal world to wreak havoc. In Demon society though Demon Spawn seem to be quite low and are simply used as fodder in battles. Imps too share a similar roll it seems, with mostly being used for simple tasks, since they are only useful in battle to swarm opponents in a tangle of limbs. Next he spoke of Reaper Demons. These Demons seem to be very primal in nature, for their sole purpose is to kill, preferably Angels. Very rarely do they have any ambition to become Demon Lords. He also mentioned Shadow Demons, creatures that excel at hiding in society and pretending to be mortal. They serve to manipulate events and spread whatever evil their god desires. Balrogs, are great monsters, well known to summoners. They are tall monsters, formed of magma and have great wings of fire and bull-like horns on their heads. Furies too are known to summoners, these creatures resemble a giant cat, but almost in the shape of a hunched over man. They are large and ferocious and well deserve the name "Fury." Shrikes are giant black buzzards that prefer to eat the living over the dead. They strike in flocks and carry their helpless opponents off to be fed upon alive.

Finally the Imp told me that many people lived there too, although they were all prisoners. They had sold their souls in life and upon death were dragged down to the Netherworld in exchange for some worldly pleasure. Or some had become unfortunate enough to make enemies with a Demon, or some other reason which I did not press. Their fates however are all the same: they are doomed to an eternity of suffering at the hands of whatever Demon has them in their fortress. Those that are still living are kept alive by unnatural means for as long as possible to prolong the suffering, for many are able to escape to Heaven upon death. But the spirits that are trapped there are trapped forever.

I then decided I had heard enough and banished the Imp back to his realm.

Day 4

For my next session I decided to summon something more challenging: a Succubi. When the demon emerged from the swirling fires of the summoning she looked upon me with such tempting lust that even with the rune circle it was hard to resist. She was as beautiful as the Imp had described and she frightened me all the more for it. I immediately decided to establish my dominance by casting a simple Holy spell. The spell made her skin boil and she screamed in agony. When she next looked at me it was with hatred. I then began the interrogation. Her name was Nvira and she seemed to serve the Drow goddess Lolth as a midlevel Succubi. I first asked her if there were different regions for each god and goddess and if they differed in appearance. She replied by telling me that yes, they do differ, but only minutely. The Chaos god Skorne's region was barren and lifeless, where as Lolth's was entangled in a great spider web, larger than I could imagine, or so she claimed. Which then spurred the question, how big was the Netherworld? She told me that it was as large as this world and only lay beneath the surface. I also asked if it could be reached simply by digging. She laughed which almost had me cast another Holy spell on her, but she answered quickly, perhaps seeing my intent. She said that in theory it was possible to dig that deep, but it would never be done, even Rat Men would never burrow that deep. She never did explain why. Al-throughout the interrogation she tempted me with her body, suggesting to me, only my strong will prevented me from succumbing. She became very persistent to the extent that she was avoiding my questions, I was then forced to banish her.

Day 15

My next summoning required much research. Summoning specific Demon types beyond Imps and Balrogs is a difficult art and mostly unbeknown to the High Elves for our foolishness in banning it. A captured Drow Witch that I came upon rotting in a cell in Syioned was able to help me. The Witch taught me, through great amounts of persuasion, the way to Summon powerful Demons. So, I wished to test my skills and summoned a Demon Lord. I first double and triple checked my rune circle to make sure that it was flawless and would hold back the potential power that was to come. When the summoning was complete a very unexpected sight stood before me. The Demon I had summoned looked like an Angel. His white clothes and hair were beautiful and almost glowed beautiful. His face was beautiful and calm and he seemed gentle. I asked him his name and he replied, "Dais." His voice too was harmonious and I was quite confused. In a chance I cast a Holy spell at him and his skin boiled, similar to the Succubi, but he did not flinch, only smiled. He claimed that the attack had been weak and wished to know why I had summoned him. My reason told me to banish him immediately, but this was too great an opportunity to give up so I proceeded with the interrogation. The conversation below is as best I could remember:

"Which dark god do you serve in the Netherworld?"

"The great lord of Chaos himself, Skorne," he replied cooly.

"Are you his First Demon Lord?"

"Haha, no, I am afraid not... yet."

"What do you do for Skorne?"

Now he seemed to become bored, "what are you doing summoning innocent demons and asking them annoying questions?"

"I wish to learn all I can of the Netherworld."

"Hmm, fascinating, I wish to learn of mortals. Perhaps you will visit my home someday and you can tell me all about them."

"That will never happen demon."

WIth a frighteningly gentle smile he answered, "we shall see."

I considered continuing but his cool demeanor frightened me into thinking that I may have inaccurately created my rune circle and he was working on a way out, so I decided to banish him immediately.

Day 20

After several other various summoning I decided to resummon Dais. Once again I will include a transcript of the conversation:

"Hmm, hello again," he said first.

"Hello."

"What did you want to know today?"

I had one question that was burning in my mind since first I saw him, "I have met many demons now and you look so different from them.... why?"

"What do you mean?"

"They are dark, and evil looking. And you look-"

"Angelic? You know, many demons were once Angels. Fallen Angels whom we have brought over to our side."

"So you were once an Angel?"

He chuckled, "no, I have always been what I am since I was first created."

"How were you created?"

"How were you created?"

"By my mother and father."

"Ah, just like a Demon Spawn, between the legs of a whore. Disgusting in my opinion. "

"How dare you call my mother a whore!"

"Haha, I joke, I mean no offense. But it is disgusting. I on the other hand created myself."

"That makes no sense."

"Hmm, I suppose not to your simple mind.... I will describe it as best I can. Have you ever killed a man?"

"Yes, I have."

"Then you know that feeling, when you took his life away, the lightheadedness, the exhilaration, the ecstasy of the moment?"

"I did not find it exhilarating."

"Hmm, then disgusting, whatever the emotion you felt, I was created like that."

"I am still not comprehending you."

"People, ages ago, had emotions, much as they do today. But those emotions were just what they were, fleeting, momentary. Until I decided to become real. And then I existed."

"So.... you are an emotion, from some person?"

"Many people in fact, but yes, I am."

"So my next question would have to be, what emotion created you."

He smiled again, "next time." And then disappeared in a flash of light. I was greatly panicked at seeing this since the Rune Circle was supposed to prevent all Demons inside it from using Magics or leaving it.

Day 30

I have been debating whether I should summon Dais again after our last encounter but he had so much he seemed to willingly offer me that it would be foolish to refuse, so I decided to try again. This time I used not 1, but 7 Rune Circles. 7 by all accounts would be enough to even hold a god in place. Here is the transcript of our third meeting:

"You know, I still don't even know your name?" Dais started off saying.

"Perhaps if you answer my questions I will tell you it."

He frowned, "I do not like that game, perhaps I will be silent till you bore of me?"

"Xandel, Xandel Illuminairy."

"Nice to meet you Xandel. Now, what was it that you wanted to know today?"

"What emotion were you created from."

He laughed, "oh, still curious about that? I was just rambling on, didn't your mother ever teach you not to trust a demon?"

I of course doubted this bluff, but accepted it for the time being. "Very well, what do you think of the current First Demon of Skorne and who is he?"

"Ah, Brefnir, he is a fool, and hardly deserves the title."

"Do you want the title?"

"I will have it in time. For now I get to spend my time with you."

"Why do Demons wish to destroy mortals?"

"We don't wish to destroy you." Dais shook his head as if pitying my confusion. "None of us want to see you all die, where would the fun be in that? We are sent by our gods to create chaos in the land of the living, and then sit back and watch you wallow in your own destruction. If you all died there would be no more of that."

"But there are some who wish to kill us aren't there?"

"Oh, don't get me wrong, we do enjoy killing you, just not all of you."

"Is it possible for a Demon to become a god?"

Now he paused and thought for a moment, "yes, it is possible."

"How?"

"Why should I tell you?"

"Do you wish to become a god?"

"Hmm, I suppose, it would be fun, but at the moment I am content with who I am."

"And what would you do if you were a god?"

"I would burn this world from end to end. Drain the seas and turn the sand to glass. Kill everyone and have their skeletons scattered everywhere. Then I would destroy the Demon gods and goddesses, all who would oppose my power over the underworld. With complete control over the Demons I would invade Heaven itself and turn it too to rubble. Then kill those gods and drag the surviving Angels down to the Netherworld and cast them all into the deepest, darkest, chasm. Finally I would command my demons to jump into this pit with them, and if they refused they too would die. Together, in a tangled mass I would leave them there, but not before collapsing the entire Netherworld atop them. Thus they would be forever trapped together, in their filth. Their moans of agony and despair would be heard everywhere, for it would be the only sound left in the whole of existence."

The level of conviction and detail he described this scene horrified me and I could tell he saw that. "And... then what would you do with no one left? You wouldn't have any of the 'fun' you talked about."

He simply shrugged, "you asked what I would do, and that is it."

I then banished him.

Day 31

I have decided that Dais is too powerful to let live. Tomorrow I will summon him again and destroy him. The 7 Rune Circles held him just as I expected so I should have no trouble ending his life. He is too dangerous to live, I fear what he may do if he is not stopped now.

Day 32

I first summoned 7 Seraphim and then summoned Dais. The Seraphim immediately attacked him. Their attack was so bright that it blinded me for several moments. Then the light went away and before me stood only Dais. He smirked and approached me. I tried to scream for help but I found that my voice was gone. He crossed each ring of the Rune Circle as if they were never there. He approached me and kissed my forehead and said, "we will have much fun together in my home." He then made me write this final entry into my journal. The ink I use is my own blood for he compelled me to stab the pen into my wrist. Whoever reads this do not copy my work, do not defy demons, do not defy Skorne, do not defy Dais. Accept your life and go about your business as usual. Your life will be spared from what I am about to experience. Forgive me Feanor! I am a fool!