A/N: Filling an anonymous request on Tumblr, asking for the boys to see Cas's "reverse exorcism" power. Sorry it took so long to write, nonny!

Setting: S4, before the team is really tight-knit.

Summary: Sam never imagined one day he'd be meeting an angel. Castiel isn't quite what he expected, but he's got some wicked cool moves. And maybe he doesn't see Sam as the abomination that the others see.

Not Alone

Sam's glower deepens, watching the demon inside the devil's trap. It's smirking back at him and Dean. His smugness makes Sam uneasy. He's pretty sure this demon knows something they don't, beyond the information they're trying to get out of it.

"I'm giving you one more chance," Dean blusters, like they can afford to kill their only lead. "What's the next Seal?"

"You think I'm scared of you and that little knife?" the demon scoffs, nodding to the blade in Sam's hand. It snickers. "You boys are way out of your league."

Sam doesn't make a move, waiting to follow his brother's lead. He doesn't want this to resort to torture. He doesn't want to go there himself, and he really wants to keep Dean away from that path. What other play do they have, though?

Dean doesn't advance. Instead, he lifts his eyes to the crumbling ceiling. "Cas," he calls. "If you can hear me, I think we've got a lead on a Seal-"

A gust of wind slams through the boards across the windows, but there's no swish of angel wings. The demon's hands are raised, its leer triumphant. Both Sam and Dean duck, covering their heads as dust rains down from the ceiling and the timber begins to creak.

"Dean?" Sam shouts, noting the uncertain grit of his brother's teeth.

The demon laughs, thrusting its hands forward. The wind roars, the gale tearing the boards away from the windows completely; the wood under their feet cracks. Dean lunges as a crevice runs from the doorway across the room—straight through the paint of the devil's trap, and now the demon is free. It grabs Dean by the throat before the Winchester can change course, then throws him into the wall to slump unmoving to the floor.

Sam doesn't stop to consider his next move, flinging himself between the demon and his fallen brother. He wields the knife as though he's unafraid, but his heart pounds. If only he could use his powers, but it's been so long since he's seen Ruby and he knows he can't count on that right now. This fight is not going to end in his favor.

"Run and hide, little boy," the demon taunts him.

Sam holds his position. He won't abandon Dean, even if it means both of them die today.

"It's more fun if I get to chase you. We have plans for you, Sam Winchester. So run. Hide. I'll be right behind you as soon as I finish with your brother."

"You're not going to touch him," Sam snarls.

The demon laughs. "You have no idea what you're dealing with, do you? You think I'm just some low-level nobody? I trained under Alastair himself."

"You still have to get through me, first."

Another laugh. "Even with that pig-sticker, you know you can't beat me. You're all alone and I'm too strong for you."

The wing beats are so soft, so subtle, Sam almost doesn't hear them. But the angel Castiel is now standing just in front of him, and suddenly the demon doesn't look so confident.

"He's not alone," Castiel growls, all gravel and thunder.

The demon's mouth opens, head tipping back. Clearly, it doesn't like its odds now that there's an angel in the mix; it's bailing out.

The cloud of black smoke only makes it halfway out of the host's mouth before Castiel has advanced in another flap of wings. Sam's eyes grow wide as he watches Castiel's hand shoot out, trapping the smoke, slowly shoving it back into the host. He's gaping at the show of power and now the demon writhes in fear.

"And I'm too strong for you," Castiel finishes, seething. Two fingers press against the demon's forehead and it collapses to the ground. Castiel turns slowly back to Sam.

The blue eyes are piercing and Sam can't help but look away. Castiel's first words to him echo in his shame-filled mind: "Sam Winchester… the boy with the demon blood." Had he really thought an angel, who could thrust a demon back into a host with his bare hands, would ever deign to see him kindly?

The fact is, Castiel is terrifying.

"Are you alright?" the angel asks him now.

Sam nods, turning to look over his shoulder. Dean's out but he'll be fine now. He hears a soft noise from Castiel and looks up to see the angel's eyes crinkling slightly at the corners. Not smiling—he's not sure Castiel even can smile—but seeming lighter somehow.

"He could have killed you," Castiel states. "Standing your ground was… incredibly foolhardy. And incredibly brave."

"He would have killed Dean if I'd run."

The crinkles deepen and the searching blue eyes don't release Sam's gaze. "I suppose I was wrong."

"About what?"

Castiel leans over and grasps the unconscious demon by the collar, hauling him half off the floor. "After watching humans for so long, I believed I would never be surprised by one again."

His free hand falls on Sam's shoulder; there's respect and compassion in the warm grip, leaving Sam to swallow back a sudden lump in his throat. Then Castiel is gone, and his prisoner with him.

Behind him, Dean is beginning to groan and stir, but Sam's mind reels with everything that's just happened. The sheer power Castiel possesses. The lack of animosity the angel has shown him. The solidarity in his grip.

And the utter, exhausted relief he feels in the idea that maybe they aren't as alone as he'd once believed.