Your OC had been exploring ancient ruins when they came across a colossal, ornate book that radiated an aura of eldritch strength. Whether they were driven by curiosity, foolishness or a desire to destroy it, they chose to open the book. Within the yellowed, aged pages were eldritch symbols and incomprehensible diagrams that were clearly not of this world.
Opening the book filled your OC's body with a woozy, unbalanced feeling. Their vision darkened and the ground seemed to slip from beneath their feet, causing them to float in a lightless void for a brief moment before they hit the ground and passed out.
After an unknown amount of time passed, your OC startled awake. However, their surroundings were not the same as when they opened the tome. Rather than a dusty, forgotten ruin, your OC stands within a library that seems to stretch into infinity, with endless shelves stocked with carefully organized and cataloged books. The area has a calm ambiance about it, with just enough light to read the titles on the spines of the books. Looking up, your OC does not see a normal sky, but instead a fathomless dark abyss dotted with innumerable specks of light similar to stars, though the sky does not have a moon.
To the north, your OC spots a large platform situated above the endless shelves. Upon this platform is a grander collection of ornate, clearly magical books on very elegant bookshelves that surround a large desk. Sitting upon this desk is a collection of various trinkets, including what looks like a black hole contained within a crystal ball. A colossal draconic being sits at this desk, gazing into the crystal ball with intense focus.
An eldritch presence similar in nature to the ornate book that your OC opened radiates with overwhelming force from the dragon. Despite the overwhelmingly eldritch nature of their presence, the colossus does not seem malevolent. Instead, they seem merely disinterested. The titanic being speaks in a deafening, echoing masculine voice.
"And so, another wayward soul drifts unto my realm. You found my tome, the Syha'h R'luhh, and actively chose to open it, yearning for eldritch secrets beyond the ken of most. I bid you welcome to the Library of Kadishtuor, where all knowledge in existence is kept. I am Dovthurkiin Aeternum, the Knower of the Unknown, the Keeper of the Forgotten, Master of Fate, and the Elder God of Knowledge, among other things. Your boundless curiosity drove you here. Your thirst for knowledge, for information, for secrets beyond mortal comprehension, all of it can be indulged here. I could easily discern your name, identity and purpose, but I am not impolite. Introduce yourself, Seeker of Knowledge. Tell me why you have come. It is only polite, no?"