A/N: I got pondering on the SPN-brand werewolves and how they're not mindless killing machines and then I took some artistic licence.

Instinct

John's been tossing and turning restlessly for about an hour now and Dean really wishes that he'd just give up the ghost and go research or something because Dean can't get to sleep with him like that. It's bad enough that Sammy's got his elbow wedged at a really annoying angle. But John only got back a few nights ago and he was really beat up and Dean suspects that that's what's causing all the trouble.

Dean sighs as John shifts again, the rustling loud in this quiet, out-of-the-way motel where there isn't even the sound of cars passing to distract him. Sammy's lucky; his head hits the pillow and he's asleep, just like that. Doesn't matter to Sammy what John's doing or where certain elbows have been placed. Dean's eyes rove around the room for something interesting to look at. He settles on the vague shadowy lump that is his dad in the next bed, still shifting even though it's not a full-blown turn over.

John groans, which makes Dean instantly on edge and tense; ready to get up if John needs him. Then John growls and it's the kind of noise Dean imagines he makes on a particularly frustrating hunt; when the creature's more elusive than first expected. John sits up and pushes himself to the edge of the bed in one swift movement, which Dean should really be thankful for seeing as now he can't keep moving around in his bed, but there's a curl of unease in Dean's belly and he can't quite work out why.

John gets up and starts pacing the room, which he really shouldn't, not with the injuries he has. He walks up and down the long side of the room, glancing out the window and pausing at the door as if expecting something to have changed since the last time. Dean's unease slowly grows as he watches John move in a way that isn't quite his. He shuffles back quietly and holds Sammy's arm, just to be sure that he's there. John's head snaps up at his movement and Dean's unease blooms into terror when the moonlight filtering through the curtains catches John's eyes and they're not John's eyes any more.

Dean tries to slow his breathing, make it sound like he's still asleep, perhaps the thing, the thing that's not John, will carry on ignoring them. Luck isn't on Dean's side, though and the thing comes slowly towards their bed. Dean slips his hand under his pillow to clutch the blade he always sleeps with and tries to rouse Sammy with his other arm, all the while trying to look like he isn't preparing to run or fight or do whatever it takes to survive.

Sammy mumbles Dean's name sleepily, but Dean keeps shaking him, eyes fixed on the thing that's not his dad as it comes closer. Dean can't work out what the thing wants, because it's taking the slowest steps in the world, it could have killed them twenty times over by now. Perhaps it just wants a fight.

Sammy whines at being disturbed, which is when Dean decides to stop playing this waiting game. He kicks and shoves Sammy off the far side of the bed and quickly follows after, pulling Sammy up onto his feet and then standing resolutely between him and the thing. The thing hasn't sped up at all, despite its prey's actions. Dean's holding his knife out towards it and Sammy's woken up enough to know the something bad's happening and is clinging to Dean's free arm like his life depends on it.

The things stalks closer and then stops just outside the reach of Dean's blade, which is looking really pathetically small in comparison. Dean backs up and the thing follows, Sammy's whimpering now, shifting between saying Dean's name and calling for their dad to come save them, almost like a prayer. Even in the dull light, it's possible to see the thing's grin and the glint of its sharp teeth. Dean wants to say something reassuring to Sammy and maybe something cocky to make himself feel better, but he's having a hard enough time trying to stop his hand shaking. His dad trained him for this and it's all going to waste.

The thing takes another step closer but Dean stands his ground, pushing Sammy even further behind him. Dean decides to make the first move and lunges with his knife. The thing slaps it out of his hand easily and leaves two deep cuts in the back of Dean's hand. Dean's now completely unarmed, with no way to protect Sammy and the only course of action he can think of is to distract it long enough for Sammy to escape, except then the thing falls to its knees in front of Dean and grips him by his arms, clamping them to his sides.

It brings its face closer, but it isn't an it, it's still John's face but for the blue eyes with cat-like slits for pupils and a slightly odd shape to his lips where they don't fit properly over the teeth. The thing that might be John is frowning as it looks Dean over, gripping tighter and digging in its claws. Its gaze then shifts to where Sammy is trying to push himself into the wall, wide and frightened eyes fixed on the two of them. Dean doesn't like the shift of attention and tries to turn his head and shout over his shoulder for Sammy to run, to get the hell out and don't come back but he's pulled in towards the huge body in front of him and crushed to it so hard it knocks the breath right out of him.

He's being held in place with just one arm, holding him in such away that he's completely unable to do anything more than stumble over his own feet as it shuffles closer to Sammy. Sammy is edging along the wall into the corner, eyes flicking about for something he might be able to use to defend himself, but the only conceivable weapon nearby is a bedside table and that's far too big.

The thing that should be trying to hurt them, that doesn't move or behave like John but is using John's body and John's face, holds a hand out to Sammy like he's a shy dog that it wants to be friends with. It's even smiling at him, which shows off its alarmingly huge teeth, but also dimples its cheeks and crinkles its eyes in a way that reminds Sammy so much of his dad.

The thing that can't be, but just might be John then moves forward too fast for Sammy to react to or even see and he's caught up by its arm the same way Dean is being held in the other arm. Dean's hand closes around Sammy's; if these are their last moments then they're going to be there for one another. The monster that their dad's become squeezes them both so hard that Dean thinks that might be how it's going to kill them, squeezing the life out of them; hugging them to death.

The creature that Dean's still reluctant to believe is John eases up just before breathing becomes a real issue and buries its face in Dean's hair and breathes. He feels Sammy tighten the hold he's got on his hand and squeezes back. The creature then does the same with Sammy and Dean can see from where his face is pressed into its shoulder that it looks happy and is smiling into Sammy's hair.

The creature – though Dean supposes he should just accept that it's his dad, now – then lowers his head and rests his face against the side of Dean's neck, inhaling deeply, smelling him, Dean realises. He feels the hesitant touch of teeth and tenses up, though still held tight and unable to do a damn thing about the situation. The creature backs off then and turns his head to do the same for Sammy; get Sammy's scent. Sammy whimpers and Dean would squeeze his hand harder if here weren't already squeezing hard as he could.

A warm, deep, contented hum rumbles through the creature's chest as he pulls his head up to get a good look at both Sammy and Dean. The clawed hands are now rubbing slowly in what could be seen as a soothing way, Dean wouldn't go quite that far, but it's more reassuring than the earlier death grip. The creature smiles at them both, every inch their father but for the eyes and the unnaturally sharp canine caught on his bottom lip.

"My boys," says John.

The End.

I hope you enjoyed!