Unlike traditional Superman stories, Smallville saw its Clark Kent (Tom Welling) meet Lois Lane (Erica Durance) for the first time while he was still in high school. Typically, there is no sort of relationship with Lois until Clark becomes Superman and gets a job as a reporter at the Daily Planet in Metropolis.
Smallville took Clark and Lois’ friendship in a different direction. The character first encountered her in the season 4 premiere. First mentioned by name in a season 3 episode as the cousin of Chloe Sullivan (Allison Mack), Lois took a trip to Smallville to investigate Chloe’s “death”. While there, she found a naked Clark Kent in a cornfield at a time where he was being controlled by the Kryptonian side of his personality. After being restored to normal by black Kryptonite, Clark teamed up with Lois to solve the mystery of Chloe’s disappearance. Once Chloe was saved, Lois moved into the Kent Farm and remained there for some time. During season 5, she became a reporter at the Inquisitor and her journalism career took off from there, with her becoming employed at the Daily Planet in season 7.
Some may wonder why Smallville took the surprising step of introducing Lois when Clark still had such a long way to go before he could fulfill his destiny and become Superman. Interestingly, Smallville would have introduced Lois as early as season 3 if DC had granted them permission, but had to wait until season 4. According to Smallville creators Al Gough and Miles Millar, they wanted Lois on the show because they wanted to bring a new character into Clark’s life that would offer a “fresh dynamic” with him [via KryptonSite]. Smallville had just lost Pete Ross (Sam Jones III), so it made sense that a new character was needed to fill the void.
The idea behind choosing Lois was that the people around Clark in season 4 were all people who liked him. While Clark's friendship with Lana (Kristin Kreuk) wasn’t what it used to be, they were still on fairly good terms and he was still friends with Lex at this point. He also got along well with the new addition to the cast, Jason Teague (Jensen Ackles). Before Lois, the only main character Clark had a negative opinion of was Lionel Luthor (John Glover), but they didn’t have a lot of screen-time together in the early seasons. What Gough and Millar wanted to do with Lois was give him someone to interact with who didn’t like him, which was in-step with how Lois has treated Clark in some adaptations. This added a whole new kind of relationship to the series, as the two found each other highly annoying and bickered quite a bit.
Even though Smallville introduced Lois way ahead of schedule, bringing in her had its benefits. Her sarcasm and – as Clark put it – her “stuck-up” personality brought out a different side of Clark, and their scenes together added a bit of humor to the show. Perhaps what made her such an interesting addition was the notion that they even though they didn’t like each other, she was the person Clark was destined to end up with at some point in the future.