Author's Note: In the old comics Lex fell out with Superboy because he went bald. While I was watching the episode "Ryan" I realized the infinitely more traumatic event that will turn Lex against Clark for good:
Monsters And Angels
Some things can never be undone. Some clocks can never be turned back. From this moment on, Lex knew that Clark and he could never be friends again, only enemies. He also knew that he'd never be able to trust anyone ever again.
It didn't matter that this week's meteorite-affected strangely-powered protagonist had been vanquished. All that mattered was that whilst defeating the evil-doer, Clark had accidentally done the unthinkable.
As Lex walked among the ashes, the stench of mylar filled the air. He bent down and picked up one of the many shreds of paper littering the floor. Two words were visible: Warrior Angel. Clark had destroyed his comic collection. Nothing would ever be the same again.
THE END