In the season ten episode "Luthor", Clark unintentionally visits a parallel universe where Lionel found and adopted Clark (Welling), who Lionel raised as a murderer who eventually kills Lex.
Clark unintentionally visits a parallel universe where Lionel found and adopted Clark (Welling). This was in the season ten episode "Luthor". Lionel raised as a murderer. This murderer eventually kills Lex Clark (Welling).