Clark was mending the milking machine. Lana came in.
"Clark," she declared, "a relationship based on secrets and lies is doomed..."
Clark sighed. Sometimes it felt like they'd had this conversation a million times.
"Lana!" he interrupted.
She turned those big, brown eyes up to him, hurt that he hadn't let her finish.
"I'm an alien, faster and stronger than a human. My spaceship crashed in the meteorite shower that killed your parents."
Lana's eyes rolled back. She keeled over.
"Lana!" Clark cried. He rushed her to the hospital, but it was too late. The truth had killed her.
Darn.
(I did another one that week, in which Lana doesn't die, but it's IMO pretty funny, so I'm putting it up here, too. Remember "Magnetic", when that krypto-mutant guy who could control metal could also control Lana's mind? Yeah.)
"It's the only explanation!"
"Riiiiight," Clark said, closing his locker. "'Cause it's so reasonable."
"Clark! Smallville! Reasonable?"
Okay, he'd grant her that one.
"I live with her! And it explains everything - the pink, the repetitiveness, the only having three different expressions!"
"Chloe, it's impossible."
"No, it's not! I've been digging - she got a ton of radiation, probably died, and Nell was such 'friends' with Lionel Luthor. Did you know that LuthorCorp was a pioneer in the field? And she's the perfect teenage girl, if you're a middle-aged genius lab-guy who doesn't get out much."
"Chloe..."
"It's true! Lana's a robot!"