Derek's POV
Derek was pretty sure he had broken a few speeding laws in order to get to Deaton's clinic as fast as he did.
But he didn't care. Not when the vet had rung him sounding so concerned.
Concerned about Stiles.
Rushing into the back room of the clinic with a low rumbling growl and bright red eyes, Derek resisted the urge to roar as he addressed Deaton in urgency "what's wrong? What happened? Where's Stiles?".
Calmer than Derek could ever claim to be the Emissary replied, only partly answering Derek's litany of questions with his arms crossed over his chest and a furrow in his brow "Stiles is at home, Derek. And I need you to calm down before I tell you anything else".
Clenching his fists Derek breathed out slowly through his nose, trying hard to pacify his inner wolf's urge to protect his pack, to protect Stiles. A few tense moments passed with not even a whisper between the clinic's occupants as Derek shoved the growling beast down into the recesses of his mind. Uncurling his fingers somewhat reluctantly, Derek retracted his claws, the wounds in both of his palms closing up as soon as the razor-sharp nails stopped pressing into the skin.
More time passed and Derek could tell that his eyes were still a deep burning red no matter how hard he tried to make them return to normal. Seemingly sensing that Derek was struggling and that this was probably as calm as the Alpha was going to get, Deaton finally started to speak.
"Stiles visited me today so I could run some tests to see if the Nemeton was causing his night terrors. It became evident early on that this was not the case and that Stiles is suffering because of backlash from his uncontrolled magic"
Derek frowned his eyes flashing back to green in confusion "wait, Stiles is magic?". Huffing at the interruption Deaton rose a single brow in his direction causing the Alpha to shift and mumble under his breath, embarrassed, "sorry, continue".
Deaton began speaking again, his crisp tone leaving no room for Derek to cut in with any more pointless questions. "As I was saying, I quickly diagnosed the problem and informed Mr. Stilinski of such. Whilst I admit I was surprised at the amount of seriousness he showed over the matter, I have full faith that he will learn to control his abilities. However, this is not the reason I called you here Derek. The reason I called is as I was conducting the tests on Stiles I noticed a very strong, foreign magical presence intertwined with his. I extracted some blood to make sure that this wasn't simply a symptom of the sacrifice and I'm afraid it isn't". Deaton paused and tilted his head at Derek with a somber expression "do you know what a Warlock is Derek?".
Shrugging Derek shook his head causing Deaton to sigh.
"There are four kinds of beings which can do magic, the most common are Druids, Warlocks and Potentials. As a Druid, I draw my magic from the four elements earth, air, fire and water, the relationship is balanced and therefore I am bound by their limitations. Potentials, the clue is in the name, they're individuals with the potential of becoming Druid's but do not unlock their true power through lack of knowledge, or other reasons. Warlocks gain magic by stealing it, or as they call it siphoning. Essentially they suck all the magical ability out of a person and convert it into their own magical energy".
Derek nodded along, showing he was understanding what the older man was saying "like a magical leech?". Smiling cynically at Derek, Deaton uncrossed his arms "Warlocks, I'm afraid are a bit more deadly than leeches Derek. The Potentials that have the unfortunate luck of finding themselves siphoned end up dead".
Brow furrowed low Derek digested the information Deaton had given with his usual intensity, his lips pulled into a frown. "You only mentioned three, you said there are four types of beings, what's the last one?".
Deaton pushed away from the bench, making his way towards a locked storage cupboard on the other side of the room, Derek watching in confusion as he unlocked the door and stepped inside. After a few seconds, he emerged from the depths of the cupboard, his hands grasping a small and worn looking journal. Eyes glued to the object in his hands Deaton flipped open to a specific page before handing it across to Derek.
Fingers gently clasping in the journal Derek tilted his head, observing the slightly torn and wrinkled page. Various symbols and words were scrawled across the surface around an illustration. The ink drawing showing a figure of undetermined gender sitting cross-legged in the middle of the page, hands held aloft either side of its body with palms facing the sky. In the center of the figure spanning the length and breadth of the torso sat a tree, its thick and twisting branches made of interlocking Celtic knots.
"The fourth kind, are Sparks. People born with an incredibly rare ability to produce their own magic. They're not limited to drawing their powers from outside sources like Warlock's or Druids and are therefore the most powerful type. Some Celts believed that those gifted with a Spark came from fruit borne by the tree of life, the fruit dropping to the ground, seeds burying into the soil and then growing into a human".
Dragging his eyes away from the picture on the page Derek raised a brow at Deaton "and what do you believe?". Deaton smirked "oddly enough, I'm not a fan of the fruit-human idea Derek. The point is, Sparks are an unlimited well of power, and if a Warlock ever found a Spark… then the consequences would be dire".
Cradling the book with one hand Derek reached up and rubbed the bridge of his nose with the other "I don't understand what all of this has to do with Stiles? Or the foreign presence that's intertwined with him?".
The look Deaton gave Derek almost made him flush in embarrassment, the older man clearly thinking that the connection was obvious. Glancing back down at the page Derek chewed on his bottom lip and tried to connect the information in his mind.
Finally, it clicked. Derek stiffening his shoulders, eyes blazing bright red once again as they reconnected with Deaton's.
"Stiles is a Spark and the presence you found... It was from a Warlock wasn't it?"
Nodding Deaton placed his hands on the surgical table between himself and the Alpha, his expression grim "and by the looks of it, they already have their claws sunk pretty deep in Stiles' mind". Lips curling into a growl Derek slammed the journal shut, his knuckles turning white as he gripped it tightly to stop his claws from making a reappearance. "What do we do?".
"We need to find something to protect Stiles from the influence, a talisman of some sorts but we have to do it without him realizing. It's imperative that he doesn't suspect anything, he can't know what we do" Deaton explained, putting emphasis on his words so Derek would understand the importance. Anger flashed through Derek like a bolt of lightning, fierce and all-consuming "Stiles has a right to know! You said Warlock's kill who they siphon from right? He's in danger!".
Deaton leveled Derek with a burning glare "because right now Stiles isn't in immediate danger! We let him know something is wrong, then the Warlock will know and we haven't even figured out who it is yet! Warlock's are dangerous at the best of times Derek, but when they feel cornered? It becomes a whole lot more serious. Our best bet is to get the talisman and then go from there".
Huffing in obvious displeasure Derek jabbed an accusatory finger in Deaton's direction "fine, we do things your way. But if Stiles gets hurt because YOU decided he shouldn't be told about the Warlock, you won't just have the Sheriff to worry about".
Smirking at the unusual amount of protectiveness in Derek's tone, Deaton raised a single amused brow "I'll be sure to keep that in mind".