The Einherjar sentries patrolling the entryway to the palace vault snapped to attention as Odin strode down the stairway past them, his scarlet feast robes fluttering around his ankles. They clapped their heels together and pulled their shields in tight to their sides as they bowed their heads.

Which was lucky, because in spite of Amora’s tutoring, Loki was still only moderately competent at mimicking the exact appearance of another person, and had anyone looked too long, he was sure the illusion would not have held up. He hadn’t gotten his father’s nose quite right, or the shape of his shoulders, and the eyepatch was wreaking havoc upon his depth perception. He had twice nearly walked into a column and had only been spared a broken nose because Amora, glamoured as one of Odin’s personal Einherjar guards, had yanked him out of the way by one of his voluminous sleeves.

But he was halfway down the stairs and the only thing he could do was walk tall, pray they didn’t cross paths with the real Odin, and silently thank the All-Father that the Einherjar were taught to stare at their boots when the king passed them.

At the bottom of the stairs, one of the soldiers, the plumage on his helmet proclaiming him a captain, saluted. “My king, you were not expected—”

“Don’t talk to me,” Loki blurted.

The guard froze. “Your Majesty?”

Loki stared at him, his heart hammering. “I’m Odin,” he said quickly.

“Yes, Your Majesty,” the guard replied, his brow creasing.

“Smoothly done,” he heard Amora hiss almost inaudibly in his ear.

Pull yourself together. Loki tugged on the front of his robes, tried to think of what his father would say, but then announced just as inelegantly, “Just...visiting my treasures.” When the soldier didn’t say anything, he raised one hand and gestured stiffly down the hall, to the vault door.

The guard looked confused but did his best to paper it over with a dutiful nod. “Of course, Your Majesty. Is there anything we can do to be of service?”

“His Majesty wishes to be alone,” Amora interjected.

“Of course.” The captain dipped his head. “If you require myself or my men—”

“I won’t,” Loki replied. “But I’ll let you know if I do. But I won’t. But. So. Thank you.” He nodded. The captain, more confused than ever, also nodded. Then Loki swept down the stairs toward the vault door, trying to salvage that shipwreck of a conversation with his posture alone.

Beside him, Amora ran a hand over the beard of the sentry face she had taken on. “A few notes,” she murmured.

Loki resisted the urge to roll his eyes—it would be less dramatic than he wanted it to be with only one visible. “Of course you have notes.”

“Everything is a teaching opportunity. First, red really isn’t for you,” she said, kicking at the train of his robe. “You’re far too pale. Greens and golds would bring out the complexion much better.”

“What does that have to do with my illusion?”

“Nothing, just a general observation. Second, you forgot to change your fingernails.”

Loki glanced down at his black nails. They looked opalescent in the dark hallway, like he was capped in jewels. “No one noticed.”

“I did.”

“Yes, well. No one looks at me quite like you do.”

She shoved her shoulder against his, her armor clanking softly. “Stop it, you’re making me blush. Third, I’m Odin? Really? How are you so bad at this?”

“I panicked!”

“I should hope so. If that was you operating with a level head, I’d be concerned.”

They reached the door to the vault, and Loki slid on his father’s riding gloves, lifted from the stables with very little effort while Amora was chatting up one of the groundskeepers. The doors were protected against magic, and could be opened only by his father’s touch. He wiggled his fingers, letting his skin absorb the memory of his father’s palm prints that rested in the leather of the glove. It was a trick Amora had taught him—small details could be picked up from items of clothing: the shape of one’s shoulders written in the tailoring of a coat or the way someone’s knees bent remembered by the creases in their trousers.

“And here’s your moment, Trickster,” Amora said.

Loki tugged the glove from his hand, his fingers now carrying his father’s prints like he had been born with them, and pressed his hand to the door. With a soft click, the doors unbolted themselves before swinging open.

Beside him, Amora said, “I’m impressed.”

“Didn’t you think I could do it?” he asked.

“Oh, I was almost sure you couldn’t.”

“Well, you were wrong.”

“There’s a first time for everything.”

The walls of the vault slanted to high ceilings, and the path forward was lined with dark, polished stone that splintered into short walkways. Each led to an alcove holding one of the treasures of the Asgardian king, some hunted down with the aid of the Godseye Mirror.

Loki looked over at Amora as her guard face slimmed, the beefy skin suctioning so that the cheekbones popped and the chin turned smooth and pointed. The shoulder-length hair stretched like a snake uncoiling, spilling into a long plait. The clothes didn’t change at first, but the body beneath them did. Slowly, the garments adjusted to match, the armor vanishing as the tunic and trousers fit to size.

Amora slicked a hand over her face—her real face—leaving behind the light dusting of freckles that sugared her nose and cheeks. She did many things well, and perhaps chief among them was knowing how to look good while doing all those things. Every movement seemed orchestrated so that if it were to be immortalized in a mural upon a palace wall, the viewer wouldn’t be able to look away. And she was never prettier than when she returned to herself, shimmering and changeable as a flame for those few seconds before she settled into her own skin, an eagle landing with its wings unfurled.

In response, Loki’s return to his form was more like the flight of an awkward pigeon. Odin’s silhouette fell away, turning in a manner that always felt liquid, like it might flow into any mold and fit any shape it chose. It could. But, instead, he let it fall into himself, his resting appearance, trying not to shy at the way his own body felt so small and brittle.

Amora, who had been watching his transformation with a critical eye, grinned. “There’s that smile.”

Loki scowled at her.

She started off down the walkway, peering into each alcove as they passed. “Have you ever been down here?”

Loki chased after her, tugging up one of those magnificent boots that had slipped down past his knee. “Never without my father. He brought Thor and me when we were young.”

“What a lovely father-son outing. There’s nothing quite like showing your children all the ways the world could end that you have stored in the basement.”

“I enjoyed it only slightly more than our trip to the killing fields on Svartalfheim.”

Amora paused in front of the path leading down to the Tuning Fork, its surface reflecting a thin band of light across her face. “So. About the boots. I’m not mad, I’m just disappointed that they look better on you. You can have them, by the way. My treat.” He glanced over just in time to catch her casting an appraising gaze up his legs. His spine prickled.

At the end of the walkway before them was the Godseye Mirror, its shimmering surface blending into the darkness. This close, it was the bluish black of a raven’s wing, but when Loki stepped up to it, it gave no hint of a reflection. He looked over at Amora as she touched a hand to the gold stave and traced one of its whorls.

“You don’t have to look,” she said quietly.

But he did. He had to know what his father had seen.

“Stand there,” he said, pointing her to the side of the Mirror Karnilla had stood on. As she stepped out of sight, even knowing she was still there, Loki felt his skin crawl with the sudden fear of being alone. Alone and staring into the end of the world.

“Do you know how to activate it?” he called, his voice higher than he would have liked.

Amora poked her head around from behind the Mirror, braid tumbling over her shoulder. “I channel power and the staves direct it. It’s basic runic magic.”

“Right,” Loki said, like he knew anything about runic magic. He’d never even heard of it. Yet another gap in his shoddy magical education.

She ducked back to her side of the Mirror, calling, “Runes and staves direct a spell. All the sorcerer has to do is channel power through them.”

“I know that.”

He couldn’t see her, but he could practically hear the smirk. “Of course you do, princeling. Are you ready?”

Over their heads, he heard a crack like thunder. A flash of white light that he felt sear his skin.

“I’m ready,” he said.

Amora’s grasp of the energy was not as elegant as Karnilla’s had been. The lightning forked and danced around the room before finding its way to her. Loki saw the tremble in the glass as she pressed her hands to the black Mirror, then suddenly his side began to sputter with light, like a firework that could not catch. An image flickered, then died, then flickered again, too blurred to be seen clearly.

“It needs more power!” Loki called to Amora, and he heard her draw a deep, ragged breath. The air around them shimmered again.

The image began to sharpen into rows of soldiers. Not soldiers of Asgard—they had no armor, no banners, and they looked instead like feral creatures, pale and foaming and bloated. They were pouring from the observatory that connected Asgard to the Bifrost, along the rainbow bridge toward the capital. A lone figure stood out among the masses of soldiers, planted at the door to the observatory, the glint of a blade in his hand. But the image was too smoky to make out much detail.

Loki balled his hands into fists at his side. He wanted to reach into the scene, wanted to grab this unknown person by the shoulders and demand to know who he was, even if it meant looking into his own face.

“It’s not enough!” he called to Amora as the image flickered again.

“This is all the energy I can summon!” she shouted in return.

Loki leaned forward, pressing his fingers against the glass. Show me, he thought. Show me who it is.

The image flickered, flushed with a clarity that didn’t last long enough for him to make sense of what he was seeing. It was there, right at his fingertips, his future.

He hadn’t realized his own power was gathering in his hands until it burst free. The surface of the Mirror burned with white light, and Loki tumbled backward, his hands searing. He heard Amora cry out on the other side of the Mirror, and he threw his arm up against the impossible light radiating from their combined power, washing out the vision entirely.

The Mirror shattered. The cracks seemed to begin at a point in the center, and then it collapsed upon itself, caving into a slick dust studded with shards as long and sharp as his knives. Several buried themselves in the walls. Loki threw his hands over his face, but Amora cast a spell, some kind of barrier, so that the shards flying toward them bounced off. One flew sideways to the alcove across from them, striking the Tuning Fork. A single crystalline note echoed through the room, so high and clear Loki felt it more than heard it, even over the sound of the breaking Mirror. It rattled his teeth. All the lights in the alcove flared, then winked out, casting them into darkness.

Loki sat up, a fine layer of black dust blossoming from his clothes. He felt coated in it. Across from him, Amora was doubled over, coughing, her blond hair darkened from the dust. He crawled forward to her, his palms burning. “Are you all right?”

She rubbed a hand over her face, smearing the dust into black streaks. “What did you do?”

“I think we overpowered it.”

“We didn’t do anything,” she snapped, tossing her hair over her shoulder. “You cast a spell.”

“It was an accident. I was trying to help you.”

“I don’t think your father will care about your intentions.”

He followed her gaze over his shoulder to the remains of the Mirror—black dust and the charred, curled outline of the staves. Panic made his stomach clench, and he thought for a moment he was about to vomit. They had destroyed the Godseye Mirror, one of the most powerful magical items in Odin’s treasure room.

I was powerful enough to destroy the Godseye Mirror.

The thought flickered through him before he could stop it. It should have horrified him. It didn’t. It thrilled him.

I am powerful.

From the darkness, Loki heard something rumble. The floor beneath them trembled.

Amora raised her head. “What was that?”

Loki climbed to his feet, one of his knives sliding into his hand as he surveyed the damage. He could feel something stirring in the darkness, some power beyond what they had funneled into the Mirror. “Stay here,” he said, turning back to Amora. “I’ll see if—”

Something grabbed him around the waist and yanked him off his feet. His knife flew from his hand, clattering somewhere into the shadows as he was thrown to the ground, landing on his back. His head slapped the stone floor and for a moment, his vision spotted.

When his eyes cleared, he heard a roar, and above him loomed a massive creature, purple skinned and six feet tall, with a shining bald head and a grotesque face, blunt teeth poking from beneath its thick lips. Its shoulders were built like boulders, and its barrel chest swelled. The monster’s mouth gaped open in a roar, its skin ropey with veins and muscles as it brought down a fist toward Loki. The Trickster rolled out of the way, his heartbeat spiking with panic. The creature roared again, its torso bulging, and suddenly a third arm sprang from its side. Loki scrambled backward, watching in horror as it seemed to grow a foot taller. Its next steps toward him smashed craters in the stone walkway.

But it reeled backward unexpectedly, letting out a roar of pain. Amora was somehow no longer sprawled on the floor of the alcove, but behind the beast, plunging a shard from the Mirror into its back. It swiped at her with a six-fingered hand the size of her head, but she ducked, rolling under its legs to Loki’s side.

“What is that?” she cried, her voice almost lost in the roar of the creature.

“The Lurking Unknown.” The struck Tuning Fork must have summoned it. He had seen it before in the arena where the warriors were tested before they joined the ranks of the Einherjar. It was summoned by a note from the Tuning Fork, able to form and wither away and then form again and again, whenever called. The Lurking Unknown was the final test for the Einherjar, meant to show off both their skills in combat and their ability to face their enemies with stoic calm. “It feeds off fear,” he shouted to Amora as she gathered a charge of energy between her hands. “The more afraid you are, the more it grows.”

The third arm the creature had sprouted looked more shriveled than it had a moment before, as though calling it by name had weakened the creature’s hold on them, but Loki still felt a strong whoosh of air as the Lurking Unknown swiped at them with it. Amora sent a blast of hot blue energy toward it in return, but the flame was extinguished against its skin. Loki scrambled for his second dagger. His hands were shaking; the monster was growing, and it was his fault—his fear’s fault. All the power he had felt flooding him moments before suddenly wilted.

You are not powerful. You are weak. You are afraid. You are beyond your own control.

“How do we defeat it?” Amora called to him, fumbling to pry out another one of the Mirror shards buried in the wall.

“You fight it without fear,” Loki replied, though the words felt impossible. “Until it fades away.”

But the Lurking Unknown was not fading. It was growing. A fourth arm sprung from its side, windmilling through the air and catching Amora across the face, sending her flying into the wall. Then it rounded on Loki and seized him by the throat. He choked, struggling to get his own hand up to the creature’s neck. As soon as he felt his fingers brush the ropy cords of muscle in its throat, he conjured his knife and stuck it hard. The monster reeled backward with a scream of pain, dropping Loki as thick black blood coursed down its neck.

Loki landed in a crouch, gasping for air, but he hardly had time to collect himself.

The Lurking Unknown had already yanked the dagger from its neck and flung it at Loki, who dodged, but not fast enough. The knife clipped his cheek before it struck the wall and clattered to the stone.

The creature raised a hand to strike again, but Amora leaped high enough to wrap her legs around its neck and use the momentum of her jump to toss it to the ground. The whole vault seemed to shake as it landed on its back. Amora stood tall on top of it, her heels digging into its chest hard enough to draw more of that dark blood. She conjured another shock of energy between her hands and sent it barreling toward the creature’s face. It screamed again. Its body seemed to shrink and grow at the same time, Amora’s calm battling Loki’s fear.

But once again, the energy from her blast seemed to absorb into its skin. It grabbed Amora by the legs and whipped her off her feet, tossing her across the room like she weighed nothing. She struck one of the columns along the wall with a crack, collapsed at the bottom, and lay still.

Suddenly Loki felt a different kind of fear entirely—his fear for Amora greater than his fear for himself ever could be. And the creature was growing, the dull bricks of its teeth becoming sharper and another arm sprouting from its back. It made a hulking lurch toward Loki. He stepped backward, his foot catching the edge of the walkway, and he slipped down into the space between the path and the wall. The stone crumbled beneath the creature’s foot as it took a few lumbering steps toward the door.

Loki heaved himself back up onto the walkway, the turned-up stones tearing his clothes. If there was a spell to stop the Lurking Unknown, he didn’t know it. The creature let out a howl, then threw its shoulder into the door at the end of the vault, splintering it. A second hard shove burst it open. Loki heard the shouts of the surprised soldiers beyond it.

Amora was suddenly at his side, her face spattered with blood from a gash in her forehead. “You’re bleeding,” he said.

“So are you.” She threw out a hand to him and dragged him along. He felt the pull in his rib cage. “Come on.”

Outside the vault, the creature had continued its rampage, and with each shocked soldier that it met, it grew, feeding off their fear until its shoulders were straining against the ceiling, knocking chandeliers from their hooks. Fighting the Lurking Unknown in the sparring ring was one thing—it was another entirely to fight it without warning. It snapped the tops of the Einherjar’s spears as they jabbed at it, their calls to each other feathered with panic as they tried to step into an attack formation, only to find themselves cut off by the stone-crushing footfalls of the Lurking Unknown. One of the soldiers must have managed to break away, for the gong warning of an attack began to bellow through the hall, drowning out the scream of the monster.

From the doorway to the vault, Loki watched, frozen, as the creature smashed an Einherjar—one of Loki’s sparring teachers, the man who had taught him to hold a sword properly and to keep his knees bent when he parried—into the wall, and he slumped, lifeless. Loki didn’t know what to do.

Then the creature let out a scream of a different sort than its hulking battle cries. The sound bore the same crystalline resonance of the struck Tuning Fork. Its body began to shrink, shriveling and curling in on itself. Loki stared at the writhing creature as it shrank to the floor—Loki’s size, then half his size, then small enough to fit in his hand, and then...nothing.

Loki looked up.

Karnilla and Odin were standing at the top of the stairway, Karnilla with a hand still extended from the spell she had cast to stop the Lurking Unknown. She started toward them, her skirt reshaping into trousers so that the train didn’t drag through the blood of one of the Einherjar that was dribbling down the steps. Odin stayed where he was, his arms folded and his face still, his anger betrayed only by his reddening cheeks. Behind him, his personal guard of Einherjar stood, their spears extended. The two in front looked as though they were trying very hard not to let the horror show on their faces. Behind them was Thor, his eyes fixed on Loki.

Odin signaled to his men, and they trotted down the stairs, joining Karnilla as she examined the fallen soldiers, checking for injuries that would require a healer, and those already beyond help.

“Loki,” Odin called, and his tone was like the misplaced step that cracks the surface of an icy pond. Loki raised his head and met his father’s cold stare. He felt a trickle of blood run down his cheek and resisted the urge to wipe it away. “Explain this,” Odin demanded.

Loki glanced over at Amora. She was staring at Odin with the sort of unapologetic ferocity that Loki wished he could turn on his father. But under Odin’s stare, he crumpled. “I’m sorry, Father.”

“Why did you come here?” Odin demanded, his eye still on his son, and Loki knew that whatever he said next would feel trivial and feeble. Odin had the power to make anything seem stupid just by hearing it.

“We came to look into the Godseye Mirror,” Loki mumbled, trying to keep his chin raised, though he was sure everyone could sense the hollowness of the gesture.

“And what happened when you looked into it?” Odin asked coolly.

Loki swallowed. “We destroyed it.”

Whatever Odin had been expecting, it was clearly not this. The stony set of his face slipped for a moment, and raw shock coursed over his features. Shock and fear. “You did what?”

“It was an accident.”

“You destroyed the Mirror?”

His father didn’t sound angry—he sounded afraid. Loki felt his own heart, still slowing itself after their fight, pick up speed again. His father was afraid of him. Afraid of his power. Afraid of anyone who was strong enough to destroy an artifact like the Godseye Mirror. The same realization—I am powerful—this time left him cold. Now Odin knew the truth, knew the extent of his son’s gifts, knew he was too powerful to be unleashed. Powerful enough to lead an army against Asgard.

Perhaps Amora sensed it too. Perhaps that fear chilled her. Perhaps she knew Loki would never be a contender for the throne if the court understood how deep his power ran. Whatever it was that made her act, she stepped forward, her shoulder brushing against his, and faced Odin. “It wasn’t Loki who destroyed the Mirror,” she said. “It was me. I channeled energy into the Mirror, and I was too strong, and I destroyed it.”

At the base of the stairs, Karnilla froze. Amora glanced at the sorceress, and Loki thought she looked proud of herself, like the power that had shattered the Mirror had been hers alone, and she relished it. Odin’s face changed, shifting back into its set of anger, though Loki caught a flicker of relief that made him sick. Odin sighed, running a hand over his face, then nodded to the Einherjar soldiers at his back. “Arrest her.”

The color drained from Amora’s face. “What?”

“No—” Loki called, but the Einherjar were already upon them. One of them, in an attempt to seize Amora, crashed into Loki and knocked him to the ground. They grabbed Amora by the elbows, and when she fought, they wrestled her arms behind her back and forced her to her knees. Amora shrieked in surprise and pain, trying to squirm out of their grip, but before she could conjure a spell to free herself, the Einherjar had her bound with a set of the chains they used in the dungeons to suppress magic in foreign prisoners.

“Father, please!” Loki cried, struggling to his knees, hating the look of supplication but unable to stand fast enough without tipping over. “I’m complicit as well.”

Odin did not look at him. “Stay back, my son.”

“Then arrest me too!” Loki cried, his voice breaking. “I was trespassing; it was my idea!”

“I said stay back!” Odin roared, then shouted to the soldiers, “She’ll await judgment in the dungeons.”

The Einherjar began to drag Amora away, but she dug in her heels, trying to fight their grip. When her legs gave out, they kept dragging her so that the raw stones torn up by the Lurking Unknown slashed her trousers until blood ran down her legs. “Let go of me! Karnilla, please! Karnilla, don’t let them do this to me!”

Karnilla turned away.

Loki wanted to follow Amora. He wanted to chase down the soldiers, demand her release, or throw himself into the cell after her, surrendering the protection she had just granted him. But he couldn’t move. He was pinned like an insect to a board, caught in his father’s gaze as Odin started down the stairs, taking in the wreckage with a weary expression. “Thor,” he called behind him. “Take your brother to your chambers and wait for my instructions.”

Thor edged forward, skirting the banister like the Lurking Unknown might spring to life again from wherever it had vanished. He extended a hand to Loki, but Loki didn’t take it. He stood on his own. It was a halting stagger more than an actual “stand.” Not the defiant gesture he’d hoped for.

As they left the vault, Thor tried to pull Loki’s arm over his shoulder, but Loki jerked away. “What are you doing?”

“You’re hurt.”

“Yes, but I’ve not lost a leg.” Loki touched a hand to his face before wiping away the thin trail of blood. It had dripped all the way down his chin and stained the collar of his tunic. He walked ahead of Thor, his stride wobblier than he would have liked.

“Loki.” Thor easily stepped in front of him, blocking his path. “I’m sorry.”

“What are you sorry for?” Loki asked, folding his arms even though the gesture sent a sharp burst of pain across his ribs. “That you missed out on all the fun?”

“I’m sorry for what I said.”

“Good, I’m glad you’re so worried about my impressionable heart.”

“I didn’t mean it. What I said about...” Thor rubbed a hand over the back of his neck. “You’d make a fine king.”

“I would, wouldn’t I?”

“And you’d never betray Asgard. No matter what Father saw.” Thor’s gaze darted from Loki’s, glancing across the hallway and the ceiling, and then he said quietly, “What did you see?”

Loki swiped the back of his hand over his cheek again, though the cut had stopped bleeding. “You and me and mother and father all together at the end of the world. One big happy un-treasonous family.”

“Please tell me.” A note of desperation punctured Thor’s voice.

“Worry not, brother,” Loki said, pushing past Thor. “It wasn’t you.”