Every stretch of peaceful slumber seemed shattered by another disturbing scene that sent her tossing against the pillows. Her nails clawed the sheets in some effort to escape her mind's eye before she finally stilled and the cycle slowly repeated itself. The last of the room's moonlight had been consumed by a rolling bank of low clouds, leaving the chamber under a dark pall without any hint of light to dispel it. Blindly, Loki listened to the agony of Jane's nightmare. Parting ways with Jane on the pretense of a strained goodnight, he had sent an illusion of himself from the chamber with a low bow while he watched unseen from the side of the heavy red curtains. Exhausted, she had quickly fallen asleep, now leaving Loki with a thousand threads to ponder following the wake of their latest encounter.

Sinking into a scrolled couch at the far side of the room, he silently cursed himself for allowing Sigyn's atlas to goad such a violent reaction from him. His brow furrowed as he recalled Jane's frantic excuse for having it—had he really given it to her? He pulled the notebook from his coat and placed it on his lap, letting his fingertips trace the intricate patterns that had been branded into the soft leather cover. There is your history of the Nine Realms. No more questions. He had uttered the words and conjured the book for Jane without the slightest intention of doing so, and his jaw clenched in renewed fury at such a thoughtless action. She had no right to use anything of Sigyn's, and yet he had more than given her permission.

"Why?" Loki growled, glaring through the dark in Jane's direction as if he expected her to respond. Perhaps he had given the answer himself when he had said she reminded him of— Loki immediately shifted the thought. It was absurd to even consider that a human could bear any resemblance to a goddess— he halted again, then grudgingly allowed it completion — much less to Sigyn. But Jane did. He felt a strange elation at the conclusion and froze, his mind scrambling to comprehend the unexpected emotion. He should feel angry that Jane had unwittingly unearthed his memories of a former beloved, but instead he felt unbidden relief wash over him as his question was laid to rest. But he would not let it rest. His quick mind took it up again, examining the answer from every angle to ask again: Why?

He stretched himself fully across the length of the couch and leaned his head back against the armrest to better stare idly at the ceiling. Similarities. There had to be similarities for the familiar chord to have been plucked in his memory. He felt a twinge of distaste at the thought of Jane and Sigyn occupying the same plane of comparison, but he reluctantly forced it down in favor of more analytic thought. That both women were fond of the stars was the most obvious trait they shared, their eagerness for knowledge bordering upon maddening passion. Loki allowed himself a small smile. How often he had fought to keep Sigyn from dragging them both headlong into danger in the name of discovery. Her zeal eventually proved contagious, however, as it usurped his once careful practicality and unleashed a reckless abandon he had never quite tempered since. Despite Sigyn's foolhardiness, her enthusiasm bore a more serious aspect, unlike Jane's grasping, childlike wonder of the world. He had flipped through Jane's bound journal of notes earlier as she slept off his magic, his eyes taking in the limitless strings of foreign symbols and numbers scribbled across the pages. Her calculations were often interrupted by detailed observations and fanciful predictions that had no true experience to support them. A folded sheaf had slipped free from the pages, and Loki recognized a crude image of Yggdrasil drawn in Thor's hand. He shook his head, chuckling to himself. Is this what Thor had been teaching her about their worlds? Lines and circles on paper: that was all Jane knew of the realms.

His thoughts wandered before falling upon a second parallel. By some unhappy chance, Jane had at times spoken with Sigyn's exact words, which left a curious uneasiness in the back of Loki's mind. She was not much like Sigyn in manner, however—Jane seemed less sure of herself at times, less eloquent even, though none the worse for words when she was provoked. She had pride and a stubborn surety about her that begged to be molded by a stronger hand. Loki conceded Jane her solid grasp of her beloved science, but he could not abide her complete ignorance of the worlds she claimed such a connection to. He longed to put her firmly in her place, to show her how tiny she was in her vast universe. To think Jane considered herself some sort of expert—his breath hitched. Had Sigyn not thought herself the same?

Loki gritted his teeth, considering. Through Jane, he had felt Sigyn for the first time in centuries, if only for the briefest of moments. The emotions he had dammed up for so long began to drip, then trickle as he felt his will begin to crack. He knew he would never see Sigyn again, and yet today he had felt her as clearly as if she were standing in the very room with him. A pang of anguish shot through Loki as he realized how he missed the woman he had met in the observatory so long ago. And now here was another, a human, so different and yet…he closed his eyes, his mind churning incessantly over it all. Curiosity finally broke through and began to gnaw at the edges of his mind until it grew ravenous, devouring his careful logic and leaving behind only a blind, voracious need to sense her again. He immediately checked himself. How close did he dare to tread before memories became nightmares, and the pain he had worked so diligently to conceal was ripped raw once more? Was a moment of illusion worth that? A sigh thrummed in his throat. How good it would feel to have her again, if only he could—

Loki's eyes shot open as the solution struck him and he grinned broadly in the dark. Jane Foster the astrophysicist, so wise in the ways of science and yet so woefully untried in her experience of it. Just how far did her likeness with Sigyn go?

Loki ran his tongue over his teeth. He would break her to find out.

"Do you mind?"

Loki's eyes flitted open. He squinted up in the brightness of the room as her face slowly came into focus above him. She was disheveled, her previous day's clothes now wrinkled as her mussed hair fell haphazardly about her shoulders. Loki's lips cracked into a slow smile as he shifted to stretch out his long limbs, now free from the stiff armor he had dissolved before sleep.

"Good morning, Jane," he sighed as he settled back onto his side and gazed languidly up at her. "You seem troubled."

"Really," she scoffed, planting her hands on her hips. "A murderous psychopath is sleeping in the same room as me and I'm supposed to be okay with that?"

Loki yawned. "I think it's a bit early to be insulting your host."

"Why are you in my room?"

"These are Thor's chambers, I believe."

Jane glared at him. "You can't even have the decency to give me a little privacy?"

"Privacy is a privilege. I have been hospitable in allowing you to stay as a guest." He pushed himself up to a sitting position and leaned forward, resting his arms across his thighs. "But I suppose that would not be a decent thing to do."

Jane stared at him. "You think that means something to me? Letting me use a few maps and books doesn't make up for anything you've done!"

Loki's smile thinned. "So called atonement was never the plan."

"Then why take me to the observatory? Why show me anything?" Jane folded her arms across her chest as she shifted her stance warily. "And all your visits, this…this spying on me! If Thor were here-"

"But he's not."

"Don't tell me you're jealous."

Loki favored her with a dour look. "If I envied Thor anything of his, you would not be it."

"Oh, thank goodness. Now I can sleep at night."

Loki's gaze roamed over the rumpled sheets of her bed before flicking back to Jane's face. "That will be a relief for you after having such bad dreams."

"You were in here when-" She let her breath out in a sharp huff as her voice rose in pitch. "You watched me while I was sleeping?"

"More like listened, really," he said with a shrug, the sunlight catching the gold patterns of his tunic as he moved. "I wanted to ensure that my guest rested well."

Jane's brown eyes blazed. "You sick, twisted-"

He tsked. "Insults, Jane."

"And you deserve every one of them! Again, why were you in here?"

Loki rose slowly, the leather around his waist creaking with the movement. "What nightmares you must have had. Tell me."

"It's none of your business."

"Everything here is my business," Loki replied serenely. A grin flickered across his face as he slowly stepped forward. "As are you."

Jane backed away in time with his advances, her jaw setting tighter the closer he came. "Get out."

Another boot forward. "Words require so little, Jane." Another step, a little louder. "Tell me about your dreams."

Jane found herself backed against a bed post, the intricate carvings of the wood threatening to dig into her back if she pressed any closer. She held her ground as he slowly continued toward her.

"Come now, I'm curious what-"

"You're the monster in them!" Jane snarled, exasperated. "Ever since I came back to Asgard, I can only get sleep in the observatory, because you're in my nightmares everywhere else!"

"I had no idea I had such…an effect on you," he purred.

"You should have stayed dead."

Loki's mouth twitched as his boots scuffed to a halt. "Perhaps you should return to Midgard where you belong."

"Like I would leave all of this behind because of you. I have so much to learn, so much I haven't done and-"

"And if I stopped you?"

"You wouldn't." She pursed her lips thoughtfully. "I think something about all this interests you too. In your own sick way," she added, muttering.

"Oh?" Loki rocked back on his heels as he fought back a triumphant smile. This had been easier than he had anticipated. "Then I have a proposition for you, Jane."

For a moment, she seemed taken aback, then quickly recovered as suspicion clouded her face. "I don't do the whole deal with the devil thing, sorry."

"Not even to explore your…oh, how do you humans term it…'outer space'?"

Jane's mouth dropped slightly. "You honestly think you could bribe me?"

A flicker of jade light left a notebook in his hand, which he held out to Jane as he swiftly closed the distance between them. "This was left in the observatory."

Jane's fingers reached out and closed around the book's spine. She paused, her eyes flicking up to Loki's when his grip would not release it. "It's mine, now give it back," she said between clenched teeth.

He tilted his head, eyebrows rising slightly. "Just how much do you know about the forces of the universe?"

She gave him an incredulous look. "I've made it my life's work, so I think I'm probably pretty familiar with it all, probably even more than you might-"

"I'll wager you know very little."

Jane stared at him as he moved even closer to tower over her. She snorted, unaffected. "And I guess you're the resident expert, huh?"

"Well, yes," Loki replied, giving her a lofty glance. "You may know of the things you study, but you know precious little about them." He wrested the journal from Jane's grasp and flipped through the worn pages." These scribbles are quite impressive, I will allow you that."

Jane snatched the book back from him, indignant. "Those scribbles are years of research that you'll never understand. Astronomical data charts, relative equations from anomaly depositions, stellar patterns-"

Loki rolled his eyes. "Please spare me the technicalities, Miss Foster, unless there is an equation that can give me a description of the nine realms."

"What do you want?"

Loki glanced innocently at the ceiling, then back down to her. "I wish to show a Midgardian scientist how little she truly knows of her world."

"I never said I knew everything."

"Mm, you seem to think so, as did Thor. Did he ever offer to show you the kingdoms of the World Tree or did he just draw little maps for you?"

"Wait, you're offering-"

"A journey through the realms, unless you would prefer to live in the observatory and imagine it for yourself, and inaccurately at that." He delighted in watching her eyes spark in an excitement that was skirted with reckless abandon, just like—he immediately shut out the thought.

When he focused on her again, Jane's face had hardened and the light had faded from her eyes. "No, I couldn't."

He leaned closer, her journal of research now the only barrier between them. "Ah, yes, the 'murderous psychopath' part, is that it?"

"A bit hard to ignore," she retorted, raising a hand to push back against his chest.

"If I wanted to kill you, I would have done it when you woke me in the observatory, and not a soul would have known. Simplest end in the world."

"That's comforting, really," Jane replied demurely as she shifted to try and slip free from his imposing frame. "As tempting as-"

Loki suddenly pressed forward, pinning her against the carved bedpost with the length of his body. He lowered his head as his voice dropped into a lilting whisper. "Have you ever seen the night falls of Álfheim, flowing silver as the very starlight runs through them? Or the caves of Nidavellir, where galaxies swirl blue and red within the living rock? The universe breathes through Yggdrasil and touches every living thing under its branches. No shuttle of yours can find these secret corners of the sky, but I can."

Jane's face was inscrutable. Loki watched her hawkishly, searching for any change in her resolve. When she failed to respond, he felt impatience gnaw away the last of his affable mood. His jaw clenched as he exhaled slowly. "Well?"

Jane pushed him away roughly. He stood still, watching her curiously as she began to pace the room, her fingers tangling in her hair. "And what do you get out of all this?"

Loki smirked. "I need to stretch my legs a bit. Dungeons are rather confining and boring, you can imagine."

"You were locked up for a reason-a ton of reasons, actually—and you should still be there! But now that you're free, you want to go on…vacation?"

Loki's fingers bent at his sides then splayed out against his leg. "It's very simple, Jane. Do you wish to see the stars or not?"

She lifted her chin and looked him directly in the eye. "Yes, but not with you."

Loki's mouth hardened. Squaring his shoulders, he took a cross step toward her as his lips drew back in a feral snarl. His right hand shot forward and a flash of green fire blazed from his fingertips. The flames struck the notebook in Jane's hands, scorching the binding as she threw it down with a shriek. In a matter of seconds the pages had curled into ash as Jane watched in frozen horror, the emerald light dissipating with the last of the intact paper.

Loki flexed his fingers and straightened his tunic as his golden armor began to gleam into place around his body. He turned his attention to tightening a newly appeared gauntlet. "Your research may need replacement. Might I suggest a study abroad?"

"You bastard!" she screamed, her glare a few degrees short of murderous. Her mouth opened to say more, but no words came as fury choked her speech.

He cinched his belt. "Care to try me again, Miss Foster? The observatory will be next, and there is nothing there of value left to me."

Jane glowered at him, then finally managed to find her voice. "Why don't you just go exploring yourself and lock me up here?"

"A clever woman will find a way to tell my secret, regardless of a lock on a door. I don't believe I could trust you in that regard."

"Believe me, the feeling's more than mutual."

Loki pursed his lips and considered her for several moments. There was still defiance in her eyes, though considerably less than he had noted at the beginning of their conversation. He almost had her. He reached down to unfasten a holster inside his coat and walking slowly up to Jane, he gently placed the object in her hands. "Use it as you wish."

Jane stared down at it and allowed her fingers to run over the intricate patterns of the leather case. "A dagger can hurt you?"

Loki shifted his jaw and looked away. "Mine can. Feel better now?"

"You'd let me kill you."

"I'd let you try."

"You really want me to go, don't you?" Her voice sounded small in her genuine wonder, though a hard edge still existed to remind him that she had not forgotten her destroyed notes.

"Think of it as an experiment of sorts. I will not offer you this opportunity again."

Jane was silent for a long moment before she finally sighed. "So I guess we start at the portal at the end of the Bifrost, is that it?"

"I prefer Yggdrasil."

Jane studied it with a puzzled expression. "It's a tree."

"No, you're standing before-"

"An entire tree."

Loki sighed, adjusting the pack of supplies that hung across his back as he took the last few ascending boulders in stride. "Touch it and tell me that it feels like one."

Jane stepped closer to the wooded shape that jutted out from the rocky soil. It seemed like a reversed root, its branches stretching out in the form of wooden claws that grasped greedily at the sky. Her fingers brushed against the bark and she immediately sprang back, reeling from the sharp sting that had pulsed from the plant.

"It's defending itself," Loki's voice came from behind her.

"It felt like a jellyfish sting," Jane winced as she continued to stare at the offending tree. "Does it have cnidocytes?"

"Have what?"

"Stinging cells. I remember looking it up once. They're these parts of an organism that explode upon contact and send out a barb into the victim so that-"

Loki drew in a deep breath. "So that is why this hurts so much." He gave Jane a rough shove forward, quickly following behind her as they broke through the electric force field. Loki gritted his teeth against the shock as Jane cried out in surprise and pain. Then they were past it, falling through a blackness traced by streaks of bright blue as Loki reached out to roughly grasp Jane's wrist. They tumbled against each other as the tunnel curved suddenly to the right before plunging down in a gut-wrenching drop. The skeins of blue were joined by ones of iridescent purple and green that raced past their peripheral vision in a swath of blurred color. Their speed quickened as they fell downward before the earthy shaft began to level out. Loki squinted as the light glowed brighter around him, burning Jane's form ahead of him into the back of his mind.

"Close your eyes!" he cried out to her.

"Already done, thanks!" was the sharp reply. The words had barely left her mouth before they slammed into solid ground in a tangle of limbs. The searing light around them had vanished.

Jane gasped for air from where she had been thrown over Loki's side. "You couldn't have given me at least one of ten possible warnings before putting me through all that?"

Loki shrugged her off as he pulled himself to his knees. "The fun is in the unexpected."

"Well, the unexpected just scared the hell out of me."

"Then you may wish to skip that realm."

But Jane wasn't listening. Her eyes widened as they took in the cavern about them as it stretched endlessly up toward the heavens. "Where are we?"

Loki gave her a proud smirk. "Welcome to Yggdrasil, the World Tree that holds and sustains the Nine Worlds. You now stand inside its very heart."

"What did we just go through?"

"One of the many branches that crop up throughout the realms. More of a twig, really."

"Are these fibers?" She ran her hand over the thick ropes that glowed beneath her knees. Silver light sprang up and swirled beneath her touch as it outlined her trembling fingers. "Oh my God, this can't be real," she breathed as she struggled to her feet. Stumbling forward and sliding along the slick filaments, she made her way to the very center of the cavern where the sound of rushing water fell in deafening torrents. Above her rose the vast trunk of an ethereal tree, the veins of bright blue and violet light pulsing and racing upward and outward in living, changing patterns. No definite form held Yggdrasil except for a wisped, silver radiance that gleamed down in crystalline threads from an eternal height, outlining an immeasurable trunk that grew and shrank as if it were breathing. Loki took it all in as if for the first time, a thrill of delight rushing through him as he felt the tree shift and sway beneath him as it stretched outward toward the stars. He had come here countless times and still the place managed to amaze him. Another cry of wonder from Jane broke his reverie, and Loki joined her where she stood before two rushing rivers that flowed in opposite directions of one another.

"I don't believe this," Jane murmured as she tilted her head upward to watch the gleaming green waters tumble above her.

"You have never seen a river flow vertically?"

"Not up into the sky!" Jane shook her head. "Is there some lack of gravitational pull? I mean, how is one going straight up and the other-" She stopped, brow furrowing. "Wait, wait…this is familiar. This looks like the part of a plant that transports…um, nutrients up and down the stem! Oh, this was in biology, wasn't it? Why didn't I pay more attention in that class? It was called…hold on a second. Um, there was a chart we had to memorize and label...Oh, yeah! Xylem and…and phloem!"

Loki watched her frenzied thought process with interest, though her scientific terms meant little to him. "Yes, I suppose-"

Jane grabbed the gauntlet around his forearm and tugged in her excitement. "It's like we've shrunk to walk around inside a living plant! I mean, we are, obviously…" Her words dissolved into silence as her gaze continued to follow the leaping waters of the upflowing river.

Loki pried her fingers from his arm. "Well, that's enough of that. This is only one small stop along the route."

"But I need to make observational notes about all this and-" Her face fell as a frown wiped the smile from her lips. "I would take notes if you hadn't burned my notebook to smithereens."

"That can be easily fixed," he muttered as he stretched forth his hand. A black leather book with thin ties appeared on the ground between them as a pen rolled out from beneath the soft front cover. "I brought a new one for the journey, if it can be of use to you."

She stared at the journal before tentatively picking up the unexpected gift. "This doesn't change anything, you know. I mean, about what you did earlier."

"Simple gratitude would suffice."

"Thank you," Jane replied, clipping each word.

"A pleasure. Now, we may as well begin with Álfheim."

"And where would that be?" Jane asked absently in between sketching rough observations in her new notebook.

"Near the top of Yggdrasil. I read that to you, do you not remember?"

"Mm-hmm." Jane scribbled on for a several seconds before stopping suddenly, her pen hovering above the paper. "Wait, do you mean we're going to climb an intergalactic tree?"

Loki laughed at her stunned expression. "No, but we will swim through one."

"You're kidding."

"Not in the least." He indicated the rushing river that coursed upward along the World Tree's silvered trunk, its waters darkening and disappearing at an unseen height. "Jump in."