A/N: Hello! I hope you enjoy, and don't be afraid to let me know what you think! (As long as it doesn't make me want to sit in a puddle of my own tears).

I do not own Supernatural. But man. Do I wish.

Sam Winchester grounded his clenched fists into the metal door. He released a shaky sigh as he forced his muscles to loosen and let his left hand fall to his side before twisting the lock with trembling fingers.

Not again, Sam thought dismally, pressing his forehead into the cool surface. And God, not like this.

He bit his lip hard enough to draw blood and slowly pulled away from the door. Sam jerked his head quickly, trying to shake out the muddled and frantic thoughts that prevented him from focusing. Dean needed him to focus.

But Sam was exhausted. Sweaty, dark hair and dirt stuck to his face. His shoulder throbbed maddeningly-clawed up by impossibly strong fingers digging their nails into his flesh. And he couldn't get the coppery odor of blood out of his nose. Sam shut his eyes against the bright fluorescent bulb buzzing right above his head. His head lolled to the side as he staggered towards the concrete wall. What he needed more than anything was to rest.

But Dean needed him more.

And that was enough to flash hazel eyes open and move long legs deeper into the supply closet of the realtor agency. Aisles of cleaning supplies and boxes of surplus pens, printer paper and ink cartridges lined his path to the back corner. He swallowed thickly when he saw his brother pressed against a shelf, head hung.

Sam hesitated, shifting slightly. Aside from the ripped, blood speckled shirt and the wide but shallow cut on his arm, Dean was fine-externally.

"Hey," Sam barely, mustered, finally finding the strength to sit down beside his older brother.

"Door's locked?" Dean asked, not bothering to glance up.

"Yeah," Sam said, nodding, "No one's getting in."

Dean quirked a morbid smile at the shared knowledge of unspoken words: No one's getting out.

They sat in silence; Dean looking down into his clasped hands, and Sam looking at him. They listened to the buzzing of the lights and the groaning of the ventilation system until finally Sam couldn't take it any longer, shattering the silence.

"I called Bobby," he explained, pulling his knees up to his chest. "We'll figure this-"

"You should go, Sam," Dean interrupted quietly, briefly glancing up at him.

Sam licked his chapped lips, ignoring him, "Bobby thinks he's on to something. Jo and Ellen are looking for the materials and they'll-"

"Sam!" Dean bellowed, now glaring at his brother with cold, green eyes. "Leave me. Now."

Sam's stomach twisted tightly, head pulsing with the terror trying to break free. No. This shouldn't be happening. Not like this. Not with Dean. Not again. This was freaking deja-vous. And of the worst unimaginable kind. Because the two brothers had dealt with a similar situation years ago, at a medical facility, in River Grove, Oregon.

Except this time, it wasn't Sam begging for Dean to leave. It was Dean.

This time, Dean was the one with the curdling fear of transforming into a homicidal psychopath.

This time, it was Dean.

And Dean wasn't immune.

Croatoan.

"No," Sam shook his head jerkily, feeling the prickle of tears in his eyes, "I'm not leaving you. You didn't leave me."

"This is damn right different, and you know it, Sam," Dean responded gruffly, his jaw tensing.

"You're right," Sam agreed firmly, feebly clinging to the remains of his strength. He had to stay strong for Dean. He had to; it was his job now. "It is different. You don't have to worry about infecting me, Dean-I'm immune!"

Dean sighed, rubbing a hand though his hair, "Sam."

Sam looked him in the eye with determinedly, "Dean."

Dean met his gaze hard and held it for a long moment before glancing down, shaking his head incredulously. He smiled sadly, "You're a stubborn little bitch."

Sam's lip quirked upwards, "Yeah, well, I learned from the best." He bumped shoulders with his older brother jokingly.

The smile on Dean's face slid away, and Sam's heart seized in his chest. If Dean began to loose hope so fast, Sam didn't know what they were going to do. "Besides," he nudged Dean gently in the ribs, "We have a few hours before..."

"I take a stroll down crazy lane?" Dean suggested half-heartedly, rubbing his eyes.

Sam pressed his lips together, "Yeah. But we're going to find something before the virus kicks in-"

"And if you don't?" Dean asked, turning his head to the side to face his brother, eyebrows raised.

Sam pushed his head into the shelf, closing his eyes and inhaling deeply. He opened his eyes slowly and looked his brother in the eye. Quietly but firmly, he answered, "I'm not leaving you, Dean."

Dean's face instantly flushed red,"Damn it, Sam!" he forcefully kicked his boot into the opposing shelf, shaking a few boxes onto the cement floor.

Sam waited patiently, watching his brother slowly regain his temper. Sam struggled to keep a blank expression, knowing that right now, his brother didn't need to be worrying about how scared Sam was about failing his brother. Of loosing Dean forever.

Grabbing his face with trembling hands, Dean stifled a dry sob. "I don't want to hurt you, Sammy," he finally choked out. He still wouldn't uncover his face.

"You won't," Sam promised calmly, "We'll take care of each other. Like we always do, right?"

"Yeah," Dean replied softly, and he eventually rubbed his fingers down his face, revealing his moist eyes.

Because Dean didn't know if that would be the case in a few hours. And that terrified him.

To be continued...