Sam Winchester is no stranger to nightmares.

The events of his everyday life would be enough to deprive a normal person of sleep, but he's evolved far past that. Only the deepest traumas are enough to disturb him or his brother from their slumber.

He still remembers being startled awake, just a few years ago, by Dean's unconscious cries, the only plea for help he couldn't suppress. Sam knows the sound of his brother's breathing cold. So he can tell instantly that the voice he hears now isn't Dean's.

"Help!"

It's plaintive, pleading, an urgent call, full of panic.

It's the sound of a child calling for a parent.

Sam skids the length of the hallway, reaching the room in a matter of seconds. The door isn't closed all the way, but cracked slightly, allowing the tiniest sliver of light into the pitch-black space.

Taking no time to shudder at the invoked imagery, Sam bursts inside, quickly ensuring that the room is devoid of tangible threats before turning to the child in the bed.

Jack is stiff as a board, eyes wide, staring at the ceiling. His posture, with the covers drawn to his chin, betrays his true, incredibly tender, age. He seems paralyzed with fright.

Sam stammers slightly, unsure of how to proceed. "Jack, are you okay?"

The kid is silent for a moment. "I...I don't...I think so."

Fumbling in the dark, Sam reaches for the desk lamp and switches it on. The light illuminates Jack's frozen face, his red-rimmed eyes.

Sam kneels next to the bed. "What happened, Jack?" He has a sneaking suspicion of what's going on. He recognizes this script—flipped from many years ago, when he was child crying out in the night.

"I..." Jack takes a deep breath, unclenching his rigid body. "I saw...my father. My real father. His eyes, they were glowing. They were reaching out...calling to me."

Sam swallows, pushing down the huge lump building in his throat. He understands what Jack has just gone through. Similar experiences used to leave him cowering in his bed, choking on silent screams.

"Then he was gone. It was dark. And I..." Jack trails off. He stares past Sam, his eyes filled with a blank kind of horror.

The kid can barely tell what's real and what's not. Empathy wells in Sam's chest, filling him with a desperate desire to soothe this vulnerable boy who so reminds him of himself. "Jack..."

He lifts his gaze at the sound of his name, looking to Sam with such trust, pleading wordlessly for him to make sense of this confusing, terrifying reality.

"You just had a nightmare, that's all. You were dreaming. Lucifer...can't get to you here. You're safe."

Jack's lips pinch together, his brow furrowing in a futile effort at remaining stoic. "It felt so real." His voice wavers on the last word.

"I know." More than anyone, Sam knows. Lucifer still stars in many of his nightmares, ones he wakes from in a cold sweat, pressing his thumb into an old, smooth scar.

Jack is new to all this, though. How could he possibly know how to process such a psychological phenomenon? It's possible that he doesn't even understand what a nightmare is.

"Dreams can feel...really real. Especially bad ones. Most times, you don't even know you're dreaming until you wake up."

Something in Sam's words, his tone, stirs Jack. He sits upright, folding his legs against his chest, both a vulnerable position and a defensive one. "You have...bad dreams, too?"

A soft smile crosses Sam's lips involuntarily at the note of sympathy, of concern, in Jack's innocent question. He isn't just curious about the answer—he feels sorry that Sam has suffered.

"Yeah, I do. Sometimes. There's no...easy answer, no way to make them stop. You just have to...get through them."

Slowly, hesitantly, Jack stretches his arm out, laying a timid hand on Sam's shoulder. "I'm sorry."

Sam exhales sharply, unable to reconcile this gentle, uncertain child in front of him with the immensely powerful being who threw him and Dean across a room just moments after being born.

It's hard to imagine that the existence of such a creature instilled so much fear in Sam, such a short time ago. Rather than destroying worlds, Jack needs comfort from bad dreams. Offering comfort to Sam, as well.

"Thanks, Jack. It's a little easier, knowing that Lucifer is...well, he can't get to me, either." He winces internally, replaying the scene of his mother falling through the rift, hands still on the devil. While Sam and this world are safe from Lucifer, his mother certainly is not.

"Did Lucifer...hurt you?" Jack ventures. He draws his arms close to his body, wrapping them tightly around his legs. "Is that what your...nightmares are about?"

"S-some of them," Sam admits. His stomach twists at the memories, and he vows to keep the whole, uncensored trauma away from the kid. "Lucifer was, uh...trapped with me for a long time. He...yeah, he hurt me.

"But when I wake up, I remember that the dreams aren't real, that...that I'm safe here with people who care about me."

"So your dreams, they never go away?" Jack's expression is a picture of despondency.

Sam wishes he could tell the kid differently. "Not really. It sucks, I know. But remember, if you get scared, or if you need something, I'm just right down the hall."

Jack smiles a tiny, sad smile upon hearing this small reassurance.

Rising to his knees, Sam claps his palm gently against Jack's face, pretending not to notice the damp streaks beneath his fingers. "Get some sleep, okay, Jack?"

"I...I'll try."

On his feet again, Sam pauses before turning to leave. "How about I leave this light on? You don't have to sleep in the dark, you know."

Jack contemplates this briefly. After just a few seconds, he nods. "That sounds...good."

"Okay. Good night, Jack."

"Good night, Sam."

No, Sam Winchester is no stranger to nightmares. But maybe, he ruminates on his way back to his own room, maybe this is a good thing.

This is one thing, one more thing that he can help Jack through. Jack won't be a stranger to nightmares, either.