Clark (Tom Welling) and Lex (Michael Rosenbaum) used to be best friends on Smallville, but Clark was never willing to tell Lex his secret. Why?
Despite their deep bond in the early seasons of Smallville, Clark Kent (Tom Welling) never told Lex Luthor (Michael Rosenbaum) the truth about his Kryptonian heritage and superpowers. Lex was just one of several characters that Clark had to hide his true nature from during his high school years in the first four seasons of the show.
Clark and Lex’s friendship began in Smallville's pilot episode, when Clark saved Lex from a car accident on a bridge. After that, Lex felt indebted Clark and was also curious about how he was able to survive being hit by a car. The two spent a lot of time together in the first two seasons, with Lex often trying to help Clark win over Lana (Kristin Kreuk). Their relationship hit it a lot of bumps, though, finally coming to an end in the beginning of season 5. An intense dislike for each other was formed later on when Lex’s morally questionable activities and manipulation of Lana made him Clark’s enemy. And then, Lex crossed over into “evil” territory in Smallville season 7 when he began killing innocent people. At the end of the season, he finally figured out that Clark was the mysterious “Traveler” from Krypton.
Lex knowing Clark’s secret made him a huge threat when he was revealed to be alive in Smallville season 8, but there was a time when Clark could have trusted him with his secret. In the early years, Lex was fiercely loyal to his friend, which was made clear on multiple occasions. Clark felt the same way about Lex, but still dodged questions when asked about the accident on the bridge and even became angry when the subject was pushed. One reason why Clark never trusted Lex with this information is linked to the Kents’ influence. Jonathan (John Schneider) and Martha (Annette O’Toole) were opposed to anyone – even Clark’s closest friends – knowing his secret. On this issue at least, Clark listened to his parents’ advice.
Jonathan believed that it would be a major problem if Lex knew too much about Clark, and a lot of that had to do with his prejudices against the Luthor family. But it’s important to point out that Clark didn’t share his father’s opinions on Lex. In the first two seasons, he wholeheartedly believed that Lex was a good and trustworthy person, so his reasons for not telling him weren’t personal. He only told Pete Ross (Sam Jones III) because Pete saw his spaceship, and he didn’t come clean with Chloe (Allison Mack) until she found her way into his Fortress of Solitude. On top of his parents’ worries about his secret getting out and the burden it came with, Clark was always troubled by the idea that if people knew if he was an alien, they wouldn’t understand.
By the time the show entered its fourth season, telling Lex the truth was no longer on the table. When Clark found out Lex was secretly compiling information on him at the end of season 3, he blew up. Their friendship was repaired in season 4, but the trust Clark had in Lex never fully recovered. At this point, it was Lex’s own mistakes that made it impossible for Clark to reveal his secret to him. Ultimately, it was his refusal to share the truth with Lex and Lex’s determination to get to the bottom of it himself that resulted in the deterioration of their friendship. Long after their bond was broken, Lex maintained a deep feeling of resentment toward Clark for never trusting him.
