Summary: Sam lets loose a secret. Dean is not impressed. Drabble, spoilers for AHBL, Part I.

"Biology"

Sam stared at the floor the entire time, unable to look Dean in the eyes. The truth was, he should have told him right away, but . . . he'd been scared to.

How do you tell someone he's sold his soul for a brother that's not even human? The answer was simple: you don't. Not if you're smart. Certainly not if you're sober.

But Sam apparently was neither. And now he's gone and blown it.

When Dean didn't speak, didn't make a sound, Sam looked up at him warily through his bangs. Dean was staring at him, his mouth hanging open a little.

Dean said, "Dude, that's stupid."

Sam blinked.

While he hadn't been expecting total agreement or even a vague affirmation that Sam could be anything other than Baby Brother Sammy, the complete disregard in Dean's voice threw him off a little.

Pissed him off, too.

"Man, did you not hear me? I said I've got demon blood in me. That makes me part monster, Dean. That makes me one of them."

Dean rolled his eyes. "Dude," he said. "It's fuckin biology, man. You give a cat a saucer of dog's blood, is it suddenly a dog? No." He polished off his beer, burped, unsteadily got to his feet.

"I mean, Jesus, Sam," Dean muttered, moving towards the bar. "I thought you were the smart one."

Sam blinked.

-Fin