<P> In season one, Lex hires Roger Nixon (Tom O'Brien), a reporter for the tabloid newspaper The Inquisitor, to discover how he survived the automobile accident where Clark saved him from drowning . All the evidence points to Clark having been hit by Lex's car, but Lex refuses to believe that is what happened so Nixon attempts to expose Clark to everyone . Around the same time, Lex also enlists the help of Dr. Hamilton (Joe Morton); Hamilton is commissioned to study the effects of the meteor rocks . Hamilton finds an octagonal disc, with unknown symbols imprinted on the disc's surface that match those on Clark's ship, while searching for traces of an alien ship that landed in Smallville in 1989 . The disc is eventually stolen by Nixon in an attempt to open Clark's ship . </P> <P> In season two, Lex's curiosity with the symbols continues . Lex first kills Nixon before the reporter can kill Jonathan Kent (John Schneider) for protecting Clark from Nixon . When Clark discovers the Kawatche Caves, under a LuthorCorp construction site, Lex opts to be the curator of the caves to preserve them after he notices symbols on the cave walls that match the symbols on the disc, as well as an octagonal shape in the wall of the cave that would fit the disc perfectly . His interest grows more and more when he finds Clark constantly in the caves, and later with a piece of paper that appears to indicate that Clark has deciphered the language on the cave walls--although, Clark denies being able to read the language . Lex's company eventually loses the Kawatche caves to Lionel as his father has also developed an interest in the caves and the octagonal disc . During all this, Lex also met and courted Dr. Helen Bryce (Emmanuelle Vaugier) but Helen would try to kill him on their honeymoon . </P> <P> Season three revealed why Lex endured Lionel's harsh parenting; his father blames him for his younger brother Julian Luthor's death, however, Lex took the blame to protect the true killer, his mentally unwell mother Lillian Luthor (Alisen Down), from Lionel's wraith . Also, Lex's curiosity into the symbols (and Clark) leads to a blowout between the two . When Lionel gives Clark a key to a room in the Luthor Mansion where Lex has been collecting information on Clark's family, Clark informs Lex that their friendship "is over". In season four, Lex replaces his father as LuthorCorp's CEO and turns his attention turns toward finding three ancient stones, which contain the same symbols as those in the cave and on the disc . He fails to find all three stones but suspects that Clark did, and used the stones to find the treasure of knowledge they were supposed to have led to, often having confrontations with Jason Teague (Jensen Ackles). Around this time, Lex's lifestyle of bedding women and then leaving them the next day would catch up to him when one (Cobie Smulders) that he had previously slept with attempts to kill him . </P> <P> In season five, Lex becomes obsessed with uncovering Clark's secret; he breaks three metahuman criminals out of Belle Reve and sends them to the Kent Farm, where they hold several people close to Clark hostage . The scheme amounts to nothing, however, and Clark cuts Lex out of life completely upon finding out . His curiosity into the symbols, which he believes to be alien in nature, results in Brainiac (James Marsters) arranging him to be possessed by the spirit of the Kryptonian criminal Zod . In season six, Lex married Lana Lang (Kristin Kreuk) after deceiving Lana into being pregnant with his child . Upon learning the truth, Lana faked her own death and attempted to pin the murder on Lex . </P>

Smallville when do lex and clark become enemies