- "I mean, i-it's like you're some kind of super... guy." - Jimmy Olsen to Clark Kent, Doomsday.
- "You play hoops? (Clark nods uncertainly) Great, cool, then we will go, uh, you know, go play a little one-on-one, and just leave it out on the court. 'Cause... I'm your bro, not your foe." - Jimmy Olsen to Clark Kent, Subterranean.
Jimmy became friends with Clark when he started working at the Daily Planet and dating Chloe Sullivan, Clark's most trusted friend. Jimmy felt that Clark resented him because he was with Chloe and tried to make peace, something which confused Clark, as he had no problem with Jimmy at all. When Gloria spawned her seeds into Jimmy, Clark and Chloe saved him; Chloe killed the plants inside him by shocking him with a defibrillator. Clark asked Chloe to help him figure out how migrant workers were dying on a nearby farm by babysitting young Javier Ramirez. Chloe and Jimmy successfully located Javier's mother in Granville, and the two were reunited.
When Lois began to suspect Oliver was the Green Arrow, she sought Jimmy to help her prove it. Clark helped Oliver by disguising himself as Green Arrow and went to rescue Lois and Jimmy from thugs in an alley. When Lois kissed Green Arrow/Clark, thinking he was Oliver, but when Oliver interrupted them, she slapped Clark. Jimmy snapped photos but Clark super-sped away and Jimmy was disappointed he didn't have the photos.
Jimmy decided to hook up Clark and Lois together on Valentine's Day. After Lois and Clark were infected by the red kryptonite aphrodisiac, Jimmy was sent by Chloe to pick up an antidote made from green kryptonite. He sprayed Lois with the antidote and she was cured. Later, Clark asked Jimmy to help him locate a paparazzi who was stalking Lana. Even though he turned out to not be Lana's stalker, Clark and Jimmy successfully found the paparazzi's apartment and tracked him down.
When Chloe turned up missing, Jimmy was extremely worried and panicked, but Clark was able to calm him down and helped him search for her. Chloe was returned seemingly unharmed and Jimmy helped her figure out who was behind her abduction. Jimmy was startled and appalled when he discovered that Clark had picked a tracking chip out of Chloe's shoulder with what they told him was a pocketknife. After he worked on a case to solve who shot Lana Luthor, he got a promotion and he left Smallville to document a swim club for elderly men in Milwaukee.
Though this isn't considered as part of their relationship, Jimmy's dream displayed a different relationship between Clark Kent and Jimmy Olsen. Jimmy was the Daily Planet's star reporter while Clark was a bespectacled, clumsy and bumbling reporter. While trying to solve a case, Jimmy tried to get into the Talon, but the bouncer wouldn't let him in, that was—until Clark showed up, suave and put-together. He didn't give details on his sudden personality change, but only asked Jimmy about story he was chasing; Jimmy wouldn't answer. Clark caught Jimmy staring at Lex and realized that Jimmy was after him.
After he killed Lex, Jimmy went to the Talon to drink out his sorrows. Chloe found him and reported that Clark was in touch with Lana Luthor, Lex's wife. It was revealed they were having an affair. Jimmy found out Lana orchestrated her husband's murder and that he would be the killer and shoots him. Lana was then shot in the back—by Clark who revealed he was an undercover detective. He was sent to watch Lex and fell in love with his wife. The dream ends as Detective Kent hauls Jimmy to the authorities.
- "Why? The world needs a hero now more than ever, Clark. Maybe meteor freaks can walk among us without being afraid. Wouldn't you want that, if one was your friend?" - Jimmy to Clark, Hero
When Jimmy came back, he was drawn to Clark's cousin Kara. When three of the competitors in the Miss Sweet Corn Beauty Pageant attacked Jimmy, Kara saved him from freezing to death. Though Clark was relieved that Jimmy was alright, he was furious with Kara for using her powers in public. When Jimmy broke up with Chloe, he spent more time with Kara.
When Clark's old school friend Pete Ross saved Kara from falling speakers, Jimmy wanted to do an interview with him, much to Pete's delight. Clark wasn't enthusiastic and, along with Chloe tried to talk Jimmy out of it. He also tried to talk Pete out of it, but the kryptonite in his system clouded his judgment. Once Pete was back to normal, he told Jimmy he couldn't do the interview and apologized to Clark for the way he behaved.
After the death of Lionel Luthor, Jimmy managed to get a glimpse of Lionel being pushed out the office window. When he and Lois went to go to the Isis Foundation, they were caught by Lex's assistant. They were placed in a freezer as Lois was shot. Clark used his heat vision to keep them warm to prevent them from dying of hypothermia.
Jimmy made a strong effort to rekindle his relationship with Chloe, but felt that she wasn't working as hard as he was. He went to Isis, only to discover a confidential document of United States Security. He went to Clark for advice, wondering why someone would lie to someone they loved. Clark told him that sometimes people lie to protect the ones they love.
- "Jimmy... I am the Red-Blue Blur. You were right. About me and about Davis. You were the only person to put it all together. I'm sorry that I lied to you." - Clark to Jimmy, Doomsday
After Clark and Chloe returned to Smallville, Chloe accepted Jimmy's proposal. The first to find out was Davis Bloome who grew a crush on Chloe. At first, he thought Clark was Chloe's fiancé because he saw them together but when he congratulated Clark, Clark was confused and surprised to find out Chloe was engaged.
Jimmy's worst fears were revealed when he found a love letter Chloe wrote to Clark when they were teenagers. Feeling betrayed, Jimmy went to the Ace of Clubs to drink out his sorrows. He met Maxima and she tried to seduce him only to realize that he was not the Kryptonian she was looking for. Clark arrived just in time and took Jimmy to the hospital. Chloe later showed Clark the love letter and when Jimmy left the hospital two days later, Chloe spoke about the letter again. Chloe explained that her feelings for Clark were in the past.
When Chloe and Jimmy were kidnapped by a crazed jeweler, Clark and Lois went undercover as a couple to find them, only to be caught in the jeweler's insane test after he let Jimmy and Chloe go. Knowing that Davis was always at the scene of the crime, Jimmy asked Davis if he could tag along with him; Davis reluctantly agreed. Clark saved both Jimmy and Davis from the shadowy creature after it tried to kill them.
While saving Lois from a thug, Clark's blur was caught on Jimmy's camera. Jimmy, excited and not knowing the Red-Blue-Blur was indeed Clark Kent, he asked Clark if he would write a story on the superhero, but Clark declined. Clark asked Chloe to convince Jimmy to drop the story but she insisted that this might be a good thing: Clark could have a secret identity. Jimmy eventually realized that Clark was indeed the Red-Blue-Blur, but Clark enlisted the help of Oliver Queen to fool him into thinking he was wrong. The plan: Clark and Jimmy cross the road and get hit by a speeding car (driven by Chloe) and Oliver (in red and blue) would come to the rescue. When Lois was in danger (again), Clark left Jimmy to save her. Jimmy was attacked by the same thug (hired by Tess) that attacked him and Lois. Oliver was confused by the change in plans, as was Chloe, but he swooped in and kicked the thug. When Clark returned, Jimmy was convinced it was him, but Clark pointed at Oliver in the cape. Jimmy was amazed as were many passers-by, who stopped to admire the hero. Noticing this, Clark wondered if Chloe was right.
When Chloe started getting amnesia, Jimmy and Clark got worried. Chloe went to Davis as he was the only person she could remember. Davis took her to the Talon and sedated her. Jimmy and Clark thanked him for bringing her to safety. Clark took Chloe to the Fortress and Jor-El took Brainiac out of her, as well as her memories of Clark's secret. Jimmy was relieved to have Chloe back.
On their wedding day Jimmy hinted to Lois that she and Clark would make a perfect couple. Clark read Jimmy's vows aloud to Lois who, at first thought that Clark was speaking to her. Clark gave Chloe the flower she gave him in their freshman year, and walked down the aisle with her and gave her away to Jimmy. It was the happiest moment of their lives - that was until a beast crashed the wedding, injured Jimmy and took Chloe away. With the help of the Legion, Clark removed Brainiac from Chloe who was taken to the Fortress that Brainiac took over. Jimmy was taken to Star City as his injuries were severe. When Jimmy came back, he saw Chloe and Davis together. He accused Chloe of not trusting him when he started getting hallucinations and left her.
Jimmy worked at the Ace of Clubs as a bartender and was hired by Lois to take pictures of a new heroine, Stiletto. Jimmy was beaten up by Bruno Mannheim who killed Ron Milano and mugged Chloe. Clark was looking for him as he had stolen Chloe's laptop with all her info on the Justice League, but Clark came into contact with kryptonite money. Lois intervened as Stiletto and kicked butt along with Jimmy but when Bruno tried to shoot her, Clark jumped in front of her and took the bullet and Jimmy came in and was able to take Bruno down. Oliver caught Jimmy stealing money from Chloe and they were both caught by Davis. Davis was about to kill them when Clark super-sped him away.
Clark tracked down Chloe and Davis' position in Edge City and went to find them, but Green Arrow, Black Canary and Impulse stopped him with a kryptonite dart. Jimmy tracked Chloe and Davis down as well, but found Clark instead. Clark tells him to remove the dart, and Jimmy notices that the kryptonite glows the closer it is to Clark, who warns him to keep it away when he puts it close. Removing the dart from Clark's back, the scratches on Clark's face healed instantly. Jimmy was amazed and Clark told him he was right all along; he was the Red-Blue Blur. Amazed by this, Jimmy called Clark a "Super-guy". Clark tells him that he needs his help and to get Chloe and Davis to his wedding present before super-speeding away, leaving Jimmy in awe.
Chloe had done as Clark wanted and used Black Kryptonite on Davis to split the human from the beast, but the monster escaped. Clark went after it. Jimmy took Chloe and Davis to the wedding present - a loft apartment overlooking Metropolis called "the Watchtower." Jimmy explained that he knew about Clark's secret and understood why she had been so secretive. They reconciled but Davis, angered by Chloe's betrayal, fatally stabbed Jimmy, who returned the favor. Jimmy told Chloe he loved her before he died.
On Jimmy's funeral, Chloe gives his younger brother Jimmy's camera, saying Jimmy would've wanted him to have it. In the distance Clark watches everyone mourn Jimmy's death. Clark goes to Watchtower and stares at the spot Jimmy had been killed. Clark explained to Chloe he placed too much faith in humanity and it was the human side of Davis that killed Jimmy and that humanity weakened him. He said goodbye and left Chloe alone in the Watchtower.
Clark arrived three weeks later, and went to Chloe after he rescued Lois in a monorail. Chloe informs him a mysterious woman is after Lois. Clark defeats her after he located her. Chloe arrives and pleads with Clark to take the Legion ring and stop Jimmy from dying, since his death was their fault. Clark refused, but Chloe begged him, saying she had given up so much for him, but Clark retorts he's not a god. Chloe leaves, remarking bitterly that Clark had nothing human left in him.
- Clark: (about Jimmy) Is he always that fired up?
- Chloe: You should see him when he's on his tenth cup of house-drip.
- - Wither.
- Jimmy: Think about how Oliver feels. Lois and Clark put this whole scheme together because they thought Oliver was Green Arrow, but then-- pow!-- the poor sucker catches her sucking lip with leather daddy [Clark].
- - Hydro.
- Chloe: What are you doing? We were supposed to take Clark out tonight, remember?
- Jimmy: Yeah, well, Lois was out alone, and then it hit me; Lois, and Clark.
- Chloe: Lois and Clark?!
- Jimmy: You got to admit, they got chemistry.
- Chloe: Yeah, so do nitroglycerin and peroxide, and I don't suggest putting them together.
- - Crimson.
- Jimmy: (to Clark about Chloe) If you hurt her, I don't care how impossibly gigantic you are, I will chop you down like a cherry tree and that... ain't no lie!
- - Trespass.
- Jimmy: What... the heck did you do to my girl, Kent?
- - Freak.
- Detective Kent: (to Jimmy) Relax, I'm one of the good guys.
- Detective Kent: I should've known better. Rule number one-- never get mixed up with a girl. Not when you're on the job.
- Jimmy: On the job? (Clark shows him his police badge) You're a cop?
- Detective Kent: Undercover unit. I was sent here to watch Lex Luthor. Falling in love with his wife, that was... that was my mistake.
- Detective Kent: (to Jimmy) Someone should've told you, kid. There are no heroes in Metropolis.
- - Noir.
- Clark: (to Jimmy) If you look at the relationship you have with this friend, do you really need to know everything about her? Or is knowing what is truly in her heart enough to know you can trust her?
- - Sleeper.
- Clark: Where were you taking it?
- Jimmy: Oh, I guess you didn't get the memo that says, "Why should I tell you?" (Clark slams him into the shelves) That's a good answer.
- - Apocalypse.
- Jimmy: Well, you might not be superhuman, Clark, but there's a reason that I thought you were the Good Samaritan.
- Clark: Why's that, 'cause I buy Girl Scout cookies twice a year?
- - Identity.
- Jimmy: Trust me. Lois and Clark would be great together. I can feel it in my gut.
- Lois: Well, take some Ex-Lax, get over it.
- - Bride.
- Jimmy: You're like some sort of Super.....guy!
- - Doomsday.