[ AN: FYI, I haven't read Magnus Chase, probably never will, so I have no idea what Rick Riordan imagines the Norse worlds as. This will be my interpretation. ]

Chapter 9: The Worldtree

Yggdrasil. It was unlike anything he had ever seen.

A tree more colossal than he could even comprehend, made of pitch-black mist yet solid as stone, its trunk stretching from horizon to horizon. They stood at the base of the trunk, and from here Percy could see roots stretching out into a bottomless void, an icy ocean, as far as the eye could see. Up higher, on various levels of the tree, were many realms, entire worlds floating in the air. It seemed to Percy like he was looking up at the layers of a transparent cake. Each world sat right on top of the other, occupying the same space, yet separate in existence, like layers of the same universe.

The tree, Percy realized, was the bridge, the glue binding the Nine Realms together. It didn't stretch up into space, it stretched through space, between dimensions. Far above that, Yggdrasil's branches spanned the width of the heavens, its every leaf and flower a star or a galaxy.

Percy blinked. He knew those stars.

Bianca followed Percy's gaze and smiled. "Wherever we go, that remains constant. Chaos is always watching over us. Remember that, Percy."

"I wouldn't be so sure of that, kid," said Anansi. The trickster spider spirit seemed uncharacteristically serious. "It's mighty dark where we're going."

Beside him, Erik nodded. "Of all the Norse realms, we are about to enter the only one where the stars don't reach."

Percy quickly ran through the list in his head. He had learned everything during his month of training, and while studying had been difficult for him, the content was interesting, and the universe was at stake, so he still remembered everything he had learned.

The Nine Norse Realms. Which one was darkest? Not Asgard, home of the gods, or Vanaheim, home of the lesser gods. Not Alfheim, land of the light elves, or Midgard, the human world, or Jotunheim, realm of the giants, or Muspellheim, the land of fire. There were only three dark worlds. Niflheim, the ice world. Myrkheim, realm of the dark elves and dwarves. And the darkest of them all, the realm at the roots of the Worldtree.

"Hel," said Percy. The word left a bad taste on his tongue.

Erik nodded. "Consider this the Norse incarnation of your Greek Tartarus. It is one of the many prisons of darkness in which Chaos kept Order contained. But lately we've heard news that strange things are happening in Hel. Traces of Order's light, radiating out of Hel and into the other eight realms. So we got to investigate. Follow me."

The group walked forward, reaching what seemed like an enormous cavern among the gigantic roots of the tree. As Percy stared into it, a terrible fear overtook him.

He was staring at the mouth of hell all over again. A different hell, sure, but the feeling was there. As if he were meeting a familiar enemy after a long time.

"I don't like this," he whispered.

"Reminds you of Tartarus, doesn't it?" asked Shanti.

"You don't have to do this if you don't want to, Percy," said Erik softly.

"I'm fine!" snapped Percy. "I'll manage. The mission comes first."

Erik looked at him in concern, then shrugged. "Alright. Bianca, you take it from here."

Bianca drew her sword, Eclipse. The darkness seemed to radiate from it like a mist, and she closed her eyes, forming glowing shapes out of it. "Alright. Here's the plan. This is the entrance to Hel. We're going to split into groups, to minimize risk of detection. Percy, you're with Erik, because this is his universe. He knows the ropes. Anansi's with you. Shanti and I will be the other group."

The mist formed into a sort of map that showed the layout of Hel. "Once we enter the cave," said Bianca, "We'll fall straight into the sky of the realm of Hel. The place is nothing like Tartarus, quite the opposite, actually. Frozen cold, near absolute darkness. No matter what, do not unequip your Chaotic armor. It's the only thing keeping our spirits alive in this Norse underworld."

Mist-shapes of various monsters appeared. Black wolves, skeletons, gigantic snakes, stone trolls. Bianca continued. "There will be, ahem, natives that we may have to deal with, as well as many thousands of human spirits. Remember, we want to minimize detection. Chaos' blessing will keep us hidden, like the Greek Mist, but there's only so much it can do. Try not to draw attention to yourselves."

Percy nodded. "Already got that lecture from Granny herself, Bianca. Anything else?"

The mist-shape shifted again, into the image of a beautiful woman, with sharp features. "There is a spirit called Brynhildr, a dead princess, whom we—Shanti and I—will be looking for. She is our contact in Hel, so finding her is important. You three, on the other hand..."

"We find the source of the light magic radiating in Hel," guessed Erik. "I have a few suspicions."

Bianca nodded. "You're looking for anything out of the ordinary. Search around any of the more dangerous parts of the realm. If you get caught, use your blessing to teleport back to Star Realm. Don't go picking fights, especially if you don't know how this mythology works. Understood, Percy?"

Percy nodded seriously.

They all shared a long moment of silence.

"Well," said Shanti. "Bianca and I should be off. Wait until we're completely through the entrance, and then some, before you follow."

"Tread lightly, everyone," added Bianca, turning toward the cavern. "Chaos be with us."

[ AN: I know it wasn't much, but I hope this chapter sates your hunger for now. The real action is coming soon. ]