Vampires on the Moon

“Take a deep breath. Okay, now swallow. Notice the difference?”
“Uhmm, we’re back in the caves?”
“Notice the sweet taste? It’s not there topside when we breathe from the air tanks.”
“Being the new guy, you probably don’t know that Matilda Langingfroth makes huge volumes of fudge for the black market.”
“It’s not chocolate you smell.”
“Oh crap. What is it? No, don’t tell me.”
“Vampires.”
“You’ve got to be kidding, right?”
“And you thought the moon was safe? I thought I was the new guy.”
“I didn’t know vampires smelled of chocolate.”
“Only on the moon. Something about the lack of oxygen. Vampires don’t need air, so they muck about over on the dark side. But the lack of oxygen affects their body chemistry. Comes out smelling like chocolate. That’s how you can tell if one is wandering about your human caves to feed.”
“Is that important?”
“It is if you smell chocolate, like now.”
“Why?”
“Vampires. Think about it.”