A/N: My first attempt at a proper Sterek story (not just my usual one-shots). The general idea for the story and the title are loosely taken from and inspired by all the mirror universe episodes from the various Star Trek installments. Poor Derek will be in for quite a ride but I like to point out that I like happy endings. Timeline wise I envisage this to take place at the beginning/middle of season 3.

Through a glass, darkly Prologue

Screams.

Pain. Piercing indescribable pain, burning through his torso.

He feels like he is about to faint, his legs unable to support his weight anymore as he slides to the ground.

Hands, red like blood but not his own, pressing against his chest, trying to stop the flow of blood.

Someone is shouting, telling him to focus, to look at them. Brown eyes staring at him, wide eyed and panicked.

His heart feels like it is about to explode. Being torn apart from the inside out. He can't stop it. The agony tears through his body, making it convulse. Flesh trying to close up only to be torn open again.

More pain, so much pain. His vision starts to blur. People around him screaming and running.

And then it gets dark and quiet, so so quiet. It's like he's being pulled away from his body. He can allow himself to just close his eyes and let himself fall.

###

BEEP BEEP BEEP BEEP BEEP BEEP

"Argh" Derek groans out as his hand flies up to his chest, clutching it instinctively. But it is absolutely fine. No gashing wound, not even a sign of blood anywhere, although he knows there should be blood. His shirt should be soaked in it but he in fact is not wearing a shirt.

BEEP BEEP

What the hell is that noise? He jerks his head up only to grunt in pain and fall straight back onto the mattress. His head is thumping, like 'having been hit with a sledgehammer over his head' thumping and the beeps are like screws that are being tightened inside his skull with each subsequent beep.

His hand fishes around the perimeter of the bed and eventually grabs hold of the offending article, and throws it against the wall where it gives up its life with a last beep.

Even with his eyes closed the bright light that is flooding the room hurts him. His room is not normally this bright. Then again he doesn't have an alarm clock either!

With that thought Derek's eyes fly open and he finds himself in an unfamiliar room, a bedroom nonetheless. Clearly someone else's bedroom. His first instinct is to check for any chains. He is not bound or otherwise restrained so whoever brought him here must not see him as a threat or an enemy.

He still has the urge to clutch at his chest, the pain of something piercing it too vivid in his head but slowly being overwritten by the very real ache that is drumming in his head. There is no other sign of life as far as he can tell. His hearing is definitely not picking up any other heartbeats but maybe his hearing is betraying him as he has trouble to focus on anything other than the pain in his head.

Where the hell is he? Where are the others? He could swear they just had been with him mere seconds ago.

And why does his head hurt like this?

He never gets headaches, just like he never gets ill. It is a most unusual and unwelcome sensation. He had always thought that humans were whiney little shits for complaining about their 'heads hurting' but now with the feeling of a drill being placed against his temple he might have to re-evaluate.

Why is his body not taking care of the pain? Is the healing process being suppressed somehow? Well, his chest seems to have healed up pretty well. He tries to focus on the pain and to force it out of his body but it ends in his head only hurting more and his vision going fuzzy.

Before Derek even gets a chance to get his bearings or contemplate why his body is acting strangely the noise of a phone ringing penetrates his already overly sensitive ears and he growls in anguish.

He buries his ears with his hands and waits for the excruciating noise to stop. After the fourth ring the answering machine picks up and Derek's blood curdles.

Someone must be playing a sick joke on him. That's the only explanation why his voice is the one on the answering machine announcing to whoever is calling that 'Derek Hale is currently not available' and to 'please leave a message'.

"Yes, good morning Mr Hale," a stiff snotty sounding female voice speaks.

"The principal would like to know why he has a classroom full of unruly teenagers and no teacher to actually teach them. So when you get this message could you please…"

"Hello?" Derek grunts down the line. He really does not have a clue as to what made him actually pick up the damn phone but for whatever reason that voice on the other end of the line seems to know him, or this impostor who is pretending to be him and he needs some answers.

"Mr Hale?" The voice asked still sounding pissy and superior.

"Yes" Derek replied impatiently, rubbing his temple soothingly with his free hand.

"Well, as I've said … the principal was wondering about your absence and …"

"Yeah, sorry, must have overslept." Derek mumbles.

"Oh, well… Alright. I guess we're all just human after all." Derek lets out a quiet snort at that. "So, can I tell the principal that you're on your way over then?"

"Er, way over to where?" Derek asks before he could think about how that must sound to the voice at the other end of the line.

"… Beacon Hills High School of course. Are you sure you're ok Mr. Hale?"

"What? I mean … yes … I fine … and yes … I'll be there as soon as possible." Derek says as he scratches the back of his head, feeling dizzy and somewhat out of place. He really doesn't know why he is agreeing to this but he needs to shed some light on this whole situation and find out who is orchestrating it and he might as well start at his apparent place of work. Dig around in the files a bit and see what he can bring up on this 'Mr Hale'. And besides that, Beacon Hills High means that at least his pack should be there and with that a chance for him to catch up with them and maybe one of them has an answer for his questions which seem to be rising exponentially.

"Oh fantastic. I'm sure the principal will be pleased to hear." The female voice said chirpily.

"Yeah, give me 20 minutes." Derek huffs before hanging up and letting out a deep sigh.

He lets his eyes wander across the room. It is plain, in design not unlike how he would decorate his own bedroom. And that is a creepy thought. He still has trouble focussing on anything for too long. His head seems to be getting progressively worse. How on earth do humans manage to function at all with these headaches? What is it they do? Ah yes, he remembers, they take painkillers! Now normally human medication doesn't have an effect on his body, but his body is not quite acting the way it should at the moment and desperate times ask for desperate measures. If there is at least a chance to get rid of this pain Derek would be willing to try almost anything at this stage.

He stumbles through the apartment. Whoever lives here surely must have some tugged away somewhere, most likely in the bathroom. He has no idea why but it's almost like he knows where the bathroom is although he is damn sure that he has never been here in his life. Admittedly the apartment is also rather small, so logically he probably just got lucky that the first door he tried was the bathroom. Overall it has a nice feel to it, compact but with a nice layout and well furnished. Other than the bedroom and bathroom Derek notices that it has a living room, a big kitchen breakfast area all connected via a fairly large corridor/entrance way.

After locating a pack he pops two painkillers in his mouth and swallows them dry before walking back to the bedroom and allowing himself a moment to sit on the bed. He probably should put on some clothes unless he wants to go out in his boxers.

Heaving his way too tired feeling body off the bed again; he walks over to the closet and rummages through it, desperately trying to find something that is not a button down or black trousers. Does whoever lives here not own something as simple as a plain shirt? And a pair of jeans would do nicely. Giving up in exasperation he pulls out a pair of black chinos and the least offensive button down he can find. Well, if this guy is really a teacher, Derek supposes it makes sense that he needs to dress up a bit.

Slowly the painkillers seem to be doing their job, the pain receding to a dull ache behind his eyes and for the first time today he feels like he can actually think. Just that now things make even less sense. There isn't anything he can think of that could shed some light on this. This is not really his area of expertise. The only thing that he can think of is possibly a spell or potion. He will have to get Dr Deaton's opinion on that later.

Ok, let's focus. First stop school. Finding his pack and trying to get some answers. He instinctively grabs the keys from the kitchen table, and wonders how on earth he knew they were there. Now he only needs to find the car that the key on the key ring belongs to.

He feels like a complete idiot walking up and down the parking lot, pressing the unlock button and hoping that one of the cars reacts. Seriously, how many cars can one medium size apartment block harbour? Finally a small black Ford beeps and flashes. Derek quickly gets in, looking around as he does so and feeling like he is somewhat stealing this car despite actually having the keys for it. Derek still hasn't got a clue which part of Beacon Hills he is in exactly but luckily the car has a built in GPS and he knows the address of Beacon Hills High.

###

Ok, so he clearly hadn't been thinking this through properly. What had he expected? To just waltz into Beacon Hills High, grab his betas (and Stiles) and make his way into the office to take a peak at his files and find all the answers to his questions? Well, whatever he had been thinking, he obviously hadn't thought about having to sit in front of a bunch of kids, all staring at him with varying degrees of boredom and curiosity, that needed babysitting. Derek has the feeling that he is not pulling this teacher act off too well so far.

On the upside (if there could be one in a situation like this), Stiles and Scott are in his class, although weirdly they're sitting at opposite ends of the classroom unlike their usual double act. Derek had tried to get their attention for the first five minutes while he rambled through the register only to be met with stares of utter indifference by Scott and some weird lopsided grins by Stiles. Well, at least Stiles seems to recognise him. Scott is still a case up for discussion.

Still, even in the close proximity of part of his pack, Derek can't shift the feeling that something is seriously out of place. They shouldn't be like this, just sitting in the classroom making small talk with their classmates like the battle last night never happened. Neither should Derek be here, sitting like it is the most normal thing in the world. Even weirder is the fact that neither Stiles nor Scott seem particularly phased by the fact that Derek is apparently their teacher. And a cold feeling of dismay briefly washes over Derek. What if they're in on this? Or what if they're all being played as a part of something bigger, something Derek just can't see?

And of all the things this Derek Hale had to teach it had to be Economics! Economics, really? What the hell does he know about economics? How long would it take this bunch of teenage delinquents take to figure out that he hasn't got a clue about what he is supposed to be teaching? And it's not like he can just flash his fangs at them to get them to shut up and show them who's in charge. He's trying hard to think back to what his teachers used to do when they basically just wanted to have a quiet time and not be bothered with actually having to teach.

"Class, listen up," Derek goes for his deep authoritative voice. "It's going to be textbook work today. Now if you could all turn to …" shit what chapter were these guys on?

"Er …" Derek thumbs through his teacher's copy, hoping, praying there will be a mark somewhere, some notes anything that could help him out here.

"Chapter 23" a voice helpfully supplies.

"What?" Derek looks up confused.

"Chapter 23, that's were we got up to." Stiles looks directly at him, flashing him another one of those cheesy smiles and waves his text book in his hand.

"Oh .. yes … of course …, thanks you S- Mr Stilinski. Just testing that you all paid attention last time." Derek says. "Now buckle down. There might or might not be a test on this tomorrow."

The class groans but thankfully that is all the protest Derek gets.

Well this should give him what, at least 30 minutes to come up with some possible scenarios as to what might be going on.

Derek pulls out a piece of paper and starts writing.

"You over there! Less talking more reading. I can't hear myself think over here." Derek snarls in the general direction of the commotion. He might as well try to keep up his act while he's stuck in here.

Back to his piece of paper. What could be causing this? Could it be a spell? That has made everyone but him forget about who they are? That would need some serious amount of magic though and Derek's not sure that even then it would work on a whole town. And why does he remember? Alternate realities? A possibility, but he even has got less of a clue how that could have happened. Then, of course there is the frightening option that he really is this Derek Hale, and is slowly losing his mind, thinking that he is a werewolf with superpowers.

Talking about powers! There must be something seriously wrong with his hearing. He can't pick up any of the guys heartbeats. And his sense of smell is off too. He had thought it was just his headache keeping his other senses at bay but now he realises that his whole body feels off, like it isn't really his own. Checking that no one is paying him any attention he puts his hands under the table and wills his claws to extend but nothing happens. Not even a tingle.

'Shit,' Derek mumbles under his breath. Is there a spell powerful enough to strip him of his powers? Or maybe he was poisoned with some kind of wolfsbane? One that suppresses the wolf? And how is he supposed to defend himself like this? This is fast turning into a proper nightmare. Worse than the one he had about being killed. Wait was that actually a dream or reality?

The ringing of the bell pulls him out of his thoughts. The class is already scrambling to its feet.

"Er … I want you all to read the next chapter and write me an essay on it by the next class" Derek has to yell to make his voice rise above the general clatter and chatter and the students general moans of complaint. Well, he has a bad day; they can just suck it up. Not that he is planning on being here tomorrow anyway.

He needs to talk to Scott and Stiles and find out what they know. Looking around the classroom he realises Scott has already left. Stiles still lingers at his desk, by the looks of it not in any particular hurry.

"S- Mr Stilinski, can I have a moment please?"

"Sure Mr Hale." Stiles says casually and continues to slowly pack his stuff. Derek thinks he clearly wants everyone to leave first which is probably a good idea in terms of keeping up appearances for now.

Finally everyone is gone and it's just him and Stiles in the room. Suddenly Stiles is on the move, walking to the door in quick strides and closing it, which earns him an approving nod from Derek. Great, at least Stiles is still using his brain. No good having anyone overhear their conversation. But then Stiles' demeanour changes and he saunters, there is no other word for it, saunters towards Derek's desk and leisurely lets his bag drop to the floor before sitting himself down on the desk brushing his leg against Derek's and leaning in, not giving Derek's personal space any consideration.

Ok… so Derek is fully aware that he and Stiles have been getting along a lot better lately, he would even tentatively call them friends. But this, this is kind of too close for comfort. And that smile he shoots him is not doing much to diffuse Derek's confusion.

"Mr Stilinski?!" Stiles smirks as his foot, which is suddenly void of a certain shoe, now purposefully moves against Derek's leg. "I have to say … I always like it when you call me that. It's kind of hot." Derek's gaze flickers from Stiles' face to where his foot is getting dangerously close to his crotch and back up at Stiles' faces, too shocked for anything to say. Evidently he really is losing his mind! That is the only logical explanation.

"You know … we should try and incorporate that the next time we play!" Stiles whispers as he leans in closer brushing his lips against Derek's ear.

And Stiles' hot breath against the sensitive skin of his ear definitely gets Derek's attention. Play?

"Stiles? What the hell?" Derek hisses and pushes Stiles away and is up out of that chair and about two feet away from Stiles so fast that Stiles for a second looks like he is kissing the air before he even realises that Derek is gone.

"Derek? What's the matter?" Stiles asks sounding more pissed than anything as he jumps off the table and takes some determined strides towards Derek.

"Stiles, what the hell was that just now?" Derek looks at him wild eyed.

"Well," Stiles smiles mischievously. "I know we agreed on no PDA, especially at school, but it's not like anyone would see us in here and anyways… I missed you. It's been three days." Stiles closes the distance pressing himself up against Derek.

"Stiles," Derek grits out between clenched teeth. "What's gotten into you! Get off of me."

"Oh, we're being Mr Grouchy Pants today. I thought you knew that it's you that's gotten into me, for quite a while already!" Stiles brings one of his hands up and tangles them in Derek's hair, pulling him down slightly.

"Well why don't you give me a little something for the road and I could be persuaded to give you your personal space you so clearly need today." Stiles says, as his hand slowly travels up Derek's left arm. And Derek's senses might not be what they normally are but he has no uncertainty about the fact that Stiles is in fact very, very aroused at this point in time.

Derek grabs Stiles by the wrist and removes his hand from his arm. "Stiles, stop! I have no idea what you're playing at here but it's not funny. Do you even know who I am?"

"What is wrong with you today? And what do you mean do I know who you are? Are you trying to piss me off or something? You were the one asking me to stay behind!" Stiles huffs out taking a step back and glaring at Derek.

"What … I, no I'm not trying to piss you off, I actually need … I just, what's going on here?" Derek motions frantically between the two of them.

"You cannot be serious?" Stiles rolls his eyes at Derek and his nostrils are flaring by now. "You know what? If you really need to ask me what is going on here between us then maybe we should give this a break … come back and talk to me when you actually know what you want. I really don't have time to deal with whatever emotional or moral crisis you're going through."

And with that Stiles picks up his bag and his shoe and storms out of the classroom.

"Stiles, wait…" Derek frantically grabs his stuff, trying to stuff them into his bag, only managing to scatter them clumsily on the floor. "Shit, shit, shit!" He curses as he picks up his stuff. By the time he makes it out of the classroom the bell rings again and there is no sign of Stiles anywhere in the quickly emptying corridors.

Fuck! He really needs Stiles to help him. Of everyone in his pack he is the one with the brains, with the ability to think outside the box and his research skills are almost legendary by now. But that somehow looks highly unlikely at the moment unless Derek finds a way to talk to him without having whatever Stiles thinks is going on between them going on. And shit! Does that actually mean that Stiles was implying he and this Hale have an actual thing going on? What even? Stiles is fucking 17! If he ever gets to meet this version of Derek Hale he is sure he is going to punch him in the face for being such an asshole taking advantage of a kid like that.

Forget trying to snoop around here for more clues. This is all going south real quick. He doesn't hold out much hope that any of the other betas would recognise him any more than Stiles and Scott did so spending any more time in this place just seems like a waste of time at this point.

His best chance for some answers probably lies with Dr Deaton. He needs some answers before he goes out of his mind. So what if he gets into trouble over leaving his place of work. It's not like he is actually working here; only that he kind of is. But really, that is the least of his worries now. And on that thought he hightails it out of the school.

###

Of fucking course. Deaton's veterinary clinic is closed and there is no sign of Deaton anywhere. Derek is walking around the perimeter. Trying desperately to find a way in but all the windows and doors are securely locked and the alarm system is live so Derek hasn't got much choice than to come back later in the hope that either Deaton or Scott will be here.

Angry and frustrated he gets back into his Ford and punches the wheel a few times. He feels vulnerable without his powers and is completely out of ideas. Who else could he try and contact? Does anyone is this godforsaken version of whatever reality this is remember him? Remember his world and what he really is?

Shit, he suddenly feels utterly alone. It's not like he isn't used to being alone, he had been for most of his adult life but somehow the presence of his pack has lured him into a weird sense of security. The feeling that he has people he can count on. He has let himself become complacent and relying on people to help him. But where are they now when he needs them? He can feel his heart beat away fast in his chest and a feeling of dread working its way up his spine and wonders if that what it must feel like to be afraid.

Because what it all comes down to is that for the first time in his life and despite everything that he has been through, Derek is afraid, really afraid.

A/N 2: I hope you enjoyed what I've come up with so far. Please let me know either way. Feedback makes for a happy (and better) writer.