Hi and welcome to my story! This is an idea I've had lurking in my brain for a while and it took me ages to write and, to celebrate my first year writing fanfiction, I decided to post it. This is my first fanfiction for Attack on Titan so if anything doesn't seem right about the characters, I'm open to constructive criticism.

I'd also like this chance to explain this AU a little more: in this world, humans have both a human form and an animal form that they can shift into at will. There will be a link in appearance with each i.e hair colour, build, etc but the one thing that stays the same are their eyes. That's how you tell a shifter apart from a regular animal.

With that said, please enjoy!

"Eren? Eren!"

Eren's eyes jerked open as he felt a sharp jab in his side, shaking him from his daydreaming. He looked around wildly for a few seconds before his eyes came to rest on a pair of smoky grey irises hovering over him intently like they were checking if he was still alive. He crossed his arms and frowned up at them.

"Mikasa! What was that for?"

"We need to head back." His sister told him bluntly, leaning her head back as she stood up straight but continued to stare down at his sprawled-out form on the ground. "The sun's beginning to go down and I don't want the whole pack out looking for us like last time."

Eren groaned as he sat up and leant against the tree behind him, rubbing his head and giving a little whine at the memory she had brought up. The last time he had kept them behind like this on a scouting trip, it had been long after dark when they had finally made it back to their camp, only to find their friends were out looking for them in the woods and their commander Shadis was ready to leave them out there the whole night after the yelling of a lifetime. Everyone had been pretty annoyed with him for making them all panic and some people had barely spoken to him for a week. Despite that experience and his reluctance to repeat it, he still looked up at her and pouted. "Five more minutes?"

"Eren," A third voice moaned as Mikasa sighed and crossed her own arms in response. Eren turned his head as his friend Armin came into view. He was the only one of the three recording where they had been and rolled up maps were spilling from his belt as he walked. He gently brushed them aside as he went to sit down on a nearby high rock, looking down at his stubborn friend with a tired look. "We've been out scouting for hours now. We're both tired and hungry and you know how Sasha eats everything, we'll be left with scraps if we don't move now. We need to go back."

Eren couldn't argue with that; Armin always had a logical answer for everything and that made it almost impossible to contradict him. He half-closed his eyes at the strained sunlight trickling down on him through the tree branches and he dug his fingers into the soft grass like he wanted to take root there. Even though he knew he had to get back to the camp of their pack, he still didn't want to leave. Outside the confining walls of their campsite was where he felt free and it sometimes took him all his strength to drag himself away from it and back behind the walls that felt like two choking hands around his neck. He enjoyed going out into his pack Maria's territory, the part of the wild land they could move through safely and regularly scouted but he still wanted more.

"Eren." Armin called his name again exasperatedly and Eren could detect worry in his voice as he looked back at him with his eyes fully open. "You were dreaming about beyond the borders again, weren't you?"

Eren defensively turned his head away from both of them so he didn't have to see his sister's disapproval. "And? So what if I was? It's just dreaming, it's not hurting anyone."

"That's not true- it's only serving to make you miserable." Mikasa told him firmly. "You shouldn't be dreaming about those kinds of things Eren, it's way too dangerous out there. What if you ran into a member of the Survey Corps? They'd have your throat ripped out before you could say hello."

Eren huffed loudly at his sister's over-protective manner but he knew her words held a lot of truth as he spat at the ground at the mention of the other pack's name. His pack Maria and the Survey Corps had been locked in war for generations, battling each other constantly to the point where nobody could remember a time there hadn't been a war. The fighting had come to a stalemate years before, when the three of them had been children, as each side grew weary of the endless fighting and losses to their ranks but even though they were no longer at war, that didn't mean they were at peace either. Each side still inspired hatred in the other and they warily stayed away, nobody daring to step into the territory the other side prowled. They all knew the simplest thing could spark the undercurrent of hatred and make it flare up again, triggering more bloody fighting, something that could be as simple as a lone animal shifter in the wrong neck of the woods.

"OK. Let's go back." Eren sighed, giving Mikasa a small smile. She returned it briefly before she hunched over like she was going to fall and transformed, her hands turning into paws before they hit the ground. In her place, a sleek black panther was now crouched ready to run, the sun shining off her sleek fur like oil as she flicked her long tail impatiently.

"Are you guys coming or what?" She asked, her normal voice coming from the panther's mouth with only a hint of a growl betraying she was in animal form.

Armin nodded and quickly went to transform, tumbling from his position perched on top of the rock and landing on the ground on the four paws of a golden Labrador retriever. His bright blue eyes that still looked human and marked a shifter from a real animal stared at Eren as he cocked his head expectantly.

"Alright, alright." Eren shook his head and laughed at them as he got to his feet and transformed. His animal form was a large timber wolf with shaggy thick chocolate brown fur and intense green eyes the colour of the leaves above them. They glared at the two of them as if to say 'Happy now?' but neither Mikasa or Armin gave a response, Armin only giving his friend a smug smile at the fact that they had finally got him to move.

Eren looked away from him with a snort and caught sight of his sister staring up at the sky with a concerned crease on her velvety forehead. The sky was beginning to lose its blue light and in the distance they could see the colours of the sunset encroaching on it gradually, turning it pink and orange as it went on its charge. They all knew it was dangerous to be out at night; the forest was a very different place in the dark and it would be all too easy for even the most experienced tracker to get lost and accidentally wonder into enemy territory.

"Let's go." Mikasa said before she took off in a sprint, her powerful limbs cutting through the air as if to defy air resistance. Eren and Armin quickly followed her, Eren managing to catch up and run alongside her whilst Armin lagged a little way behind them. He was the least athletic of the three, preferring to leave all the running and lifting to the other two, but what he lacked there he made up for in buckets with his mental abilities. His brains were highly valued among the pack and they had helped the trio out of some very tight spots before, usually ones caused by Eren being headstrong and charging in without thinking. That was one reason Mikasa stuck to his side like glue and refused to let him anywhere without her and Armin there.

Mikasa was also renowned throughout their pack for being one of their strongest soldiers, outstripping even the most experienced of warriors with her fighting skills and speed. She was such a great fighter that many of their seniors had passed comment that if there had been more soldiers like her in the Maria pack before the stalemate, the war would have been over long ago and needless blood wouldn't have been spilled.

Eren knew he wasn't exceptional with either brains or brawn but what he did have was a lot of determination, a strong sense of right and wrong that usually sent him flying into any fight he saw and earned him the reputation of being practically suicidal and a curiosity about the world beyond that he feared would never be satisfied. He looked up at the rapidly darkening sky where the outlines of birds were only just visible and sighed. He wished sometimes that he could become a bird; that way he could fly away and see all the things that were described in Armin's books. Armin had stopped letting him see them, for fear he would do something reckless and leave him with a furious Mikasa, but he still remembered every detail. The well-thumbed pages had spoken of great expanses of water that tasted of salt, rocks that reached for the skies and brushed the clouds with their tips, plains of hot sand that stretched as far as the eye could see in great golden piles. He sighed as he watched a great flock of birds caw into the air and swoop west, going further and further until he could no longer see them. There was nothing more he wanted than to see those places but he knew in his heart that they were likely to stay in his head, nothing more than dreams.

OOO

They arrived back at the camp just before sundown, making it back just behind all of the other scouting teams who had already lined up before their commander. They all had the same thing to report; no sign of any border breaks, no hint of any disturbances and no traces of any Survey Corps. Shadis nodded his head stiffly at each one, seemingly pleased with the good reports though his face still held its permanently angry expression with a stare that could wither the words on any soldier's tongue. After they had all given their verbal reports, he barked their dismissal at them and they all trudged to the dining hall, exhausted after a long days' worth of scouring their pack's territory. Only one girl appeared to have any energy left as she sprinted to be first in line, chased by a short exasperated-looking boy with a shaved head and flailing arms.

"Sasha! Wait up, the food's still going to be there in a few minutes!"

"But I'm staving Connie!" Sasha whined over her shoulder at him before she dashed through the door and left him behind. Connie threw his arms high up in the air as he gave a long sigh towards the heavens.

"I give up, nobody can talk to her when she's hungry…" He muttered crossly as he stalked in just ahead of Eren and his friends, barely noticing them as the hall erupted with overjoyed cries.

"Looks like the peace is already gone." Eren commented to his two companions as they got in line for their food and the hall filled with more noise. "It's a good thing we got back when we did."

"You mean it's a good thing you listened to us." Armin pointed out triumphantly. "If we'd stayed behind like you wanted, we would be getting the scraps Sasha left."

"Like Sasha leaves scraps." Eren said lowly as they looked over at the table where the brown-haired girl was devouring a great pile of food like it was her last meal, Connie groaning by her side as he tried to get through his own food before she started eyeing that up as well. Eren looked down at his own plate of stringy salted meat and boiled potatoes and grimaced a little. It had been a while since the pack had gone out for a good hunt and it really showed. How anyone could find this appetising, he really didn't know.

"We haven't been sent out to hunt for a good month now," He voiced his concern to Armin and Mikasa as they sat down at one of the long wooden tables and began to eat. "Do you think there's any reason why we keep being sent out for scouting missions around the borders instead?"

"Nothing's been said to us," Armin said. "But it is a little weird. Maybe they think we have something to fear that could come from outside?"

"Like an attack?" Eren suggested wide-eyed. "Maybe from the Survey Corps?"

"I don't think it's anything that drastic…" Armin hastily added. "They would have told us if those guys had been sniffing around our borders. And surely we would have noticed something amiss if they were, we're all decent trackers."

"Maybe they just haven't made their move yet." Eren said, his eyes flashing. "Maybe they're waiting to catch us off guard. In that case we should be the ones to attack first. If we were to just go over the borders…"

"No Eren." Mikasa cut him off with a glare that could have turned people into stone. "You are not going out beyond the borders and you are not getting involved with the Survey Corps. They are dangerous and I refuse to let you get yourself killed out there."

"I won't get killed out there!" Eren snapped back, his voice rising in volume as he glared straight back at her angrily. "I'm not stupid Mikasa! I want to pay them back for what they did and I want them to suffer too! I don't want to be cooped up here forever just because of them!"

"Still mouthing off about the borders Jaeger?" A smirking voice came from behind Eren that really didn't help his mood. He whipped his head round and snarled when he saw the young man with two-toned hair and round dark glinting eyes standing there, his arms crossed over his broad chest and his lips curled in a sneer as he chuckled mockingly at him. "Personally I think you should go, that way I wouldn't have to see your stupid suicidal face around here."

"Shut it horseface," Eren shot back at him. "Shouldn't you be off kissing someone's ass right now? That's the only way you're ever going to get a mate."

Jean growled lowly at him, his eyes briefly flickering over to Mikasa before they angrily settled on Eren again. It was well-known in the camp that Jean had a crush on Mikasa, one that they all knew he had no chance of ever having returned as the girl barely noticed him unless he was fighting with Eren. Jean refused to acknowledge this though and still went a little flustered around the girl, his face blushing a deep red as he glared back angrily at Eren.

"Like anyone will want a mangy dog like you." He hissed at him angrily. "When the day comes, nobody going to go near you. They probably want someone who's going to stick around instead of get themselves clawed to pieces by a member of the Survey Corps."

Eren stood up, his eyes never leaving Jean's as the bench scraped loudly against the floor and drew the attention of everyone around them. Picking a mate was deemed almost as a sacred ritual in any pack and the subject was touchy between Eren and his comrades as soon they would be of age and able to choose their mate. When somebody became 18 they could ask somebody to be your mate; if they accepted you were bonded for life and you could have no other partner but them whilst either of you were still living. It was a very serious rite of passage, equivalent to giving your heart and soul to someone, and what spooked Eren about it was that he was two months away from his 18th birthday and yet he didn't feel that way towards anyone. Still he refused to let that show on his face, especially not in front of Jean.

"You take that back!" He shouted at Jean, not caring that the other boy was taller than him as he glared with pure rage boiling in his eyes. "Or else I'll drag your ass to the stables and make sure you stay there with the rest of the horses!"

"You little fucking mutt…" Jean's barrage of insults was cut short when Eren transformed into his wolf form right in front of him, growling lowly as he bared his sharp white teeth and his shackles rose. Jean wasted no time in rising to the bait; in less than a second, he too had transformed and Eren was faced with a large chestnut stallion with a white stripe down his nose, a blond mane and tail and a wild furious look in his round liquid dark eyes.

"I dare you to say another word pony boy!"

"Call me that again and I'll kick your slobbering face in!"

"Just try! See how far it gets you!"

"Guys, please stop! You're making a scene!" At that moment, two animals leapt between the warring pair, blocking either of them from making an attack. One was a black panther who snarled at Eren protectively to make him get back; the other was a taller fully black horse that stood in front of Jean and prevented him moving any closer. The black horse gave a soft pleading whinny, his eyes full of worry as he stared in Jean's before he spoke again in a gentle low voice.

"C'mon you two, this isn't worth it. You don't want Shadis to come back in here and put you on cleaning duty again, right? So Jean let's just go back to our table and forget this whole thing? Please?"

Jean gave him a long look before he sighed and transformed back into his human self, followed shortly by the black horse who became a tall lanky boy with soft black hair and freckles peppered all over his cheeks. "OK Marco," Jean said with a small nod at his relieved best friend. "But only because you asked. You really saved Eren from getting his arse handed to him." He directed his last comment at Eren before he turned his back and stomped back to the other side of the hall with Marco in tow, who couldn't keep his eyes from the back of his blond head.

"Hey! You get back here so I can-" Eren words were brutally cut off as Mikasa's paw slammed into the side of his face, knocking him to the floor as he gave a loud yelp of pain. People hurriedly looked away as her eyes glared at them all before finally landing on her brother as he struggled to get up, his paw pressed against his cheek as he whimpered. "Mikasa! What was that for?!"

"For being an idiot." She told him bluntly, reverting back into a human as Eren did the same, exposing a red mark on his cheek. "You said you would stop picking fights with Jean."

"He was the one who started it! Didn't you hear him, he said-"

"I know but you shouldn't have risen to the bait. You have to keep your temper under control." She snapped before her eyes took on a hardness that told him she was being really serious. "Eren I don't want to hear you talking about beyond the borders anymore."

"But Mikasa…"

"No buts!" She almost shouted, her fists clenched as she stood over him. "I don't want to hear it! No more talk of revenge and going over into other territories… Do you even realise how dangerous this kind of talk is? You are my only family, I don't want what happened to Mum to happen to you too…"

"It won't!" Eren exploded as he stood up and pushed her away. "I'm not that stupid little kid anymore who needs protecting! I'm a soldier now, the same as you, and I'm going to pay the Survey Corps back for what they did and I'm going to see beyond the borders and nobody is going to stop me!"

"Eren wait…" Armin tried to intervene but he was too late; Eren had already turned around and stalked off, leaving his half-finished plate as he walked out angrily into the darkness of the night. Mikasa made to go after him but Armin grabbed her arm and held her fast.

"What are you doing?"

"Just give him some time alone. He needs to think… maybe if we give him that, he'll cool off." He sighed deeply. "He isn't trying to get himself in trouble, I think he just feels…trapped here."

"I know," Mikasa answered with a hint of bitterness in her tone. "But we're all in the same situation here. We need to focus on what is best for each other and our pack. He can't just keep dreaming about gallivanting off when we need him here." She crossed her arms with a light huff and stared off in the direction Eren had thundered in. "Maybe once he has a mate it will settle him and he will calm down."

Armin snorted. "I think it will take a lot more than that."

OOO

Eren went on walking through the barely torch-lit camp, his feet furiously pounding the ground until the voices in the dining hall were too distant to make out. All he could hear was the sound of his own raspy cross breathing and the thuds of the packed earth beneath his boots. His mind was too fogged by anger to keep track of where he was so when he finally stopped to look up at the silver-streaked sky, he found he was almost at the walls of their camp. The wall that ringed the camp was an imposing structure, made of stacked logs pointed vertically up towards the sky, each carved with a sharp point to ward off intruders. Up close in front of him, the long stretch of it that ran off into the distance either side of him almost seemed to mock his uselessness and in that moment, he would have liked nothing more than to take wolf form and tear it to shreds. Hot anger spilled through his veins like molten lead and angry tears sparked in the corners of his eyes as he stared up at the tall wooden walls they were forbidden to leave unless instructed.

Why was everyone trying to hold him back? Did they think he was that weak that he couldn't take care of himself? Were they really all happy to languish here behind these walls, never seeing beyond the ends of their noses and their desire for security? He thought of what Mikasa had said and he closed his eyes, letting the water stream down his cheeks. He knew what she was trying to say, of course he did, but he couldn't believe she didn't want revenge on the pack that killed their mother too. Didn't she feel the need to avenge her, the need to get back at them all? He didn't know but he knew he couldn't live cooped up like this. His friends just wanted him to be safe but safety was nothing if this was the cost of it. He looked back up defiantly at the sky, clenching his fists and growling like he was daring it to make a move to stop him. When it didn't and the moon carried on staring blankly down at him, he grinned. Who cares if they think I'm suicidal? He thought. I'll prove them all wrong.

He began to walk down the perimeter, parallel to the logs as he ran his hand across them. There has to be a weak point somewhere, no structure like this is perfect, he thought, pressing against each one with all his strength. There must be-aha!

He froze as one log started to give, yielding under his forceful shove and revealing a small patch of the outside through a small gap. Through it he saw a flash of forest, a hint of dark greens and brown all mashed up together like paints on a canvas. That tiny taste only served to inflame his appetite and he pushed harder, grunting as he eventually made a hole big enough for him to slide through. The log fell back into place with a light thud, like it was apologising for itself, and Eren found himself on the outside, his back against the wall as the expanse of forest stood before him, the barrier fallen away.

For a moment, he just stood there, feeling stunned by the overwhelming possibilities that stretched over the landscape like a blanket in front of his wide eyes. The cold night breeze usually kept away by the walls and their outdoor fires swept over him in its full bitterness, ruffling his hair and making the trees sway in a beckoning dance. The air smelt of pine and night flowers instead of fire and greasy food and the only sounds were the gentle rusting of the leaves and caws of various animals that seemed a million miles away from the loud chatter of the canteen. The full feeling of freedom hadn't hit him yet, slowly fizzing inside him as he attempted to absorb it all. As it built up, he found his face was almost splitting in a wide grin and he started to laugh like a child. He was free, actually, really, truly free.

Like a fuse had been lit inside him, he turned into his brown wolf form and sprinted from the camp. The forest swallowed him up like jaws and the feeling was exhilarating; he thought he would get drunk from the feeling of the wind in his thick fur alone and the night air was enough to make him giddy. He howled up at the moon, shaking birds from the trees with his volume as he charged through the woods, his paws beating the ground and his eyes darting everywhere, not wanting to miss a thing. He had thought the world was glorious before but now everything seemed brighter and the excitement made him howl again. If this is a dream, he thought suddenly, please don't let Armin or Shadis wake me up yet. Please let me have this.

He ran and ran until the trees started to blur and look unfamiliar and the grass felt thicker and heavier under his feet. He slowed down, realising he must have passed their border a little while before and that both filled him with glee and wariness. He slashed at a nearby tree, knowing he could use the mark later to work his way back and he slowly moved through the thick trees, keeping his nose to the ground. Everything here smelt different, the scents tangling in his nose and making him splutter a little when they got too strong. It was all so new and unnerving but he pushed on regardless, not wanting to turn back now. I'll just be a coward if I do, he thought gritting his teeth a little as he thought of Jean's earlier sneering words about being clawed to pieces. I'll be damned if I'll go back now.

He walked on and saw that the trees were starting to thin, gently leading him onto a thin dusty path that swiped through the green undergrowth. He followed it gingerly, almost anxious at what he would find but before those doubts could grip him and compel him to turn back, he turned a corner and stumbled from the forest onto a clear gently-sloping bank. He looked up, startled at the abrupt change, but then he caught sight of the view that stood before him and all his thoughts were stolen away.

The lake that slowly beckoned him closer was like nothing he had ever seen and he felt almost hypnotised as his feet carried him to its lapping edges. He stared down at his boots, watching the brown water go clear as it soaked the toes of his boots and he laughed again in wonder as he lifted his head back up to fully absorb the whole thing. It wasn't a big lake, he could tell that as he could clearly see the bank and all the plants on the other side but it still felt huge; there was nothing that could come close in his own territory. He stood staring at it, feeling captivated; the sheen of the brown water was like a mirror, the images of the sky above and the trees that gathered around it only marred by the soft rippling caused by the wind, making the surface look like a thousand fingers were languidly running through it. Leaves speckled it with dots of green and occasionally he caught sight of a flash of silver as a fish bobbed up to the air before diving back down again. The pulses of ripples made the lake feel alive, like a living breathing thing that was watching him just as intently as he was watching it, and the thought was thrilling to Eren as he gleefully kicked at the droplets forming on his paws. This was a treasure that he wanted to store away in his mind and never forget. He suddenly remembered the pages of Armin's books about the huge bodies of water that sat upon the land like great sunken caves of water and he wanted to childishly squeal. This may not be the ocean but it was a start at least.

He was so caught up staring at the lake in all its midnight glory that he didn't hear the set of slowly encroaching steps that warily approached him. He didn't even realise he wasn't alone until a sharp voice cut through the night air, crushing the serene atmosphere around him in a second like it was a bug under his boot.

"Who the hell are you and what are you doing in Survey Corps territory?"