Chloe and Jimmy met during the summer of 2002 during an internship at the Daily Planet. Chloe lost her virginity to him, but they then lost contact for 4 years, until the events of Dark Thursday. After that they had an on-off relationship, due to Chloe keeping Clark's secret and then discovering that she was a meteor freak.
Kara arrived in Smallville after Reeves Dam burst and released her from suspended animation. She quickly integrated herself with the people in her cousin's life and met Chloe at the Daily Planet. Chloe was wary of her at first, as she felt that all the other Kryptonians that had visited Earth proved to be violent and dangerous. Nevertheless, the loyalty that she had for Clark extended to Kara.
It wasn't long before Kara also met Jimmy, who was on assignment at the Smallville Harvest Festival when they spotted each other through the crowd. The two seemed to share a mutual attraction, which even triggered her heat vision (a sign of sexual arousal in Kryptonians ). Kara introduced herself to Jimmy as Clark's cousin from Minnesota. Much to Chloe's surprise, Kara and Jimmy quickly established a friendship, after Kara saved him from being frozen to death by the Weather Girls.
His near-death experience caused Jimmy to understand Chloe's previous assumptions that all metahumans eventually become psychotic. Nervous about what he would think of her, she kept her meteor-infection secret, but was clearly uncomfortable when he declared that he would help her rid the town of meteor-freaks. Kara interrupted them to pick up her bag. Chloe then noticed Kara and Jimmy share a long look, but didn't react.
To save her relationship with him, Chloe pursued a way to cure her infection and discovered Curtis Knox's research. To do this Chloe had to reschedule a date with Jimmy, much to his disappointment, especially as she couldn't give a reason. This sent him straight into the arms of Kara, when she asked for his help with locating her crystal from her ship. Kara relied on Jimmy's technological resources at the Daily Planet rather than Chloe's, as she lost trust in Chloe and Clark when she discovered Clark's relationship with the Martian Manhunter. Kara used a cover story that she was an ET junkie, but Jimmy didn't seem interested in the reason and offered his assistance readily, due to his obvious attraction to her. When they discovered that the ship was housed in a government warehouse, Jimmy was eager to tell Chloe but Kara convinced him not to by flirting with him. Chloe arrived and witnessed their flirting, but Kara tried to make light of the situation and Jimmy insisted it was not what it seemed.
Concerned that the treatment to cure her meteor infection would cause memory loss, she had stopped by to deliver a note asking Jimmy to not let her forget why they belong together. However, hurt by how close he seemed to be with Kara, she left abruptly, seemingly giving up on their relationship. Later, they tried to reconcile, but they both realised that there were still issues between them. Jimmy was angry that Chloe had complained about his jealousy of her ongoing close relationship with Clark, but when he came to Kara's aid on just one occassion, she also acted with jealousy. Ultimately, they decided to separate.When Kara disappeared briefly, he frequently asked Clark if he had heard from her. This only added to the tension between him and Chloe. Initially, Jimmy remained loyal to Kara and kept her secret. However, when Clark voiced his concerns of her safety, Jimmy was also clearly concerned about Kara. He then admitted that he thought she might be in Washington looking for the spaceship that Lois had found.
When Clark found Kara and brought her back to Smallville, she immediately visited Jimmy and invited him out for lunch. Jimmy was pleased to see Kara again and was glad that she was safe. When he told her that he will always there for her, she kissed him. Jimmy was stunned by this but thrilled that she seemed to be as attracted to him as he was to her. He ran into Chloe on the way out. Still keen to be friends, she also invited him out to lunch. When she discovered he already had plans with Kara, she was visibly disappointed. She warned him to be careful, as they are from different worlds. After seeing Kara's impetuousness, Chloe was still wary of her. Suspecting her jealousy and unaware of the irony, Jimmy insisted it was not like they were from different planets. Chloe watched them leave with trepidation.Dismissive of Chloe's warning, Jimmy continued his relationship with Kara and took her for weekend surfing trip to Coast City. However, their closeness was short-lived, as shortly afterwards Kara got amnesia and disappeared. Despite their once close relationship, Jimmy made no attempt to contact or find Kara. Chloe, on the other hand, did everything she could to help Clark find Kara although she seemed to do this for Clark rather than to help Kara. Although she was always friendly to Kara, Chloe seemed to be cautious around her. During Kara's absence, Jimmy reconciled with Chloe after she confessed her meteor ability, however, they still had a rocky relationship, due to Jimmy's ongoing feelings for Kara.
When Kara returned to Smallville still with no memory, Jimmy was keen to remain close with her and took her to a OneRepublic concert. He was very understanding about her memory loss and was keen to help, which she was receptive to. However, Jimmy could not provide her with the answers she was looking for and she began to get close with Lex.
Chloe inquired how things were going between Jimmy and Kara, to which Jimmy explained the difficulties he was having with her amnesia. Chloe seemed sympathetic but, when Jimmy invited her for a drink, she was pleased that it looked like they were starting to repair their relationship. Jimmy then lost contact with Kara.
Chloe, on the other hand, remained protective of Kara, largely for Clark's sake. She rescued Kara from the Luthor Mansion to avoid Lex discovering her secret, restore her memory and powers, and to help save Clark. She seemed to have forgiven Kara and Jimmy's previous relationship as there was no sign of resentment or jealousy towards Kara and she even admitted to being "a fan" of Kara's. This showed that she was now secure in her relationship with Jimmy. When Kara disappeared again, Jimmy showed no concern and made no attempt to contact her, clearly putting his feelings for Kara behind him as he concentrated on his relationship with Chloe.
When Kara started to act erratically, Chloe proved that her allegiance was to Clark rather than his cousin, as, although she admitted that she liked Kara, she was able to objectively see the damage that she could cause and she insisted on confronting her. However, this version of Kara proved to be Brainiac in disguise, while the real Kara was trapped in the Phantom Zone. Chloe was ultimately able to free Kara from the Phantom Zone. When Kara returned, Chloe did not look pleased, obviously still nervous of her impetuous behavior that she had exhibited in the past. Kara's return was short-lived as she realized that she did not fit in in Smallville. She didn't try to contact Jimmy before she left and instead just flew off into space to search for Kandor, leaving Chloe and Jimmy to embark on their future together.