Smallville

Season 4, Episode 17

Episode Title: Onyx

Air Date: 2005-04-13

Overview:

A black kryptonite explosion splits Lex in two and his evil side - Alexander - is released. Alexander imprisons Lex in the mansion then gives full vent to his evil side - he threatens to evict Lana from the Talon unless she becomes his mate, jousts with Lionel, and tries to kill Clark and Chloe when they figure out his secret.