|“||Well Little Gilbert, it was nice to have a brother for a second there when you weren't being so damn annoying.||”|
Jeremy officially met Katherine for the first time in Masquerade, while she was posing as Elena. He wasn't fooled by her act, and knew who she really way. He delivered a message to her from Stefan and Damon, and told her that they were ready to hand over the moonstone. When Katherine asked him why they would send him as a messenger, he informed her it was because they knew that he wasn't afraid of her.
He met her again in The Sacrifice, when he tried to retrieve the moonstone from the tomb she was locked in, underneath the ruins of Fell's Church. He successfully retrieved the moonstone; however, she attacked him and fed on him until Stefan eventually saved him.
In The Reckoning, Katherine kidnapped Jeremy when she found out from Bonnie that Jeremy could contact Anna, as he is a medium. She decided to use to get information from Anna about Mikael. After they got the information, Katherine and Jeremy became partners in order to find Mikael in the cemetery in Charlotte. When they reached the cemetery, Katherine tries to awaken him by using blood from various animal and human sources, but it doesn't work. Later, after Mikael fed on Katherine and drained her, it is presumed Jeremy told Mikael to look for Klaus in Mystic Falls, and helped Katherine after she was drained.
In Down The Rabbit Hole, Jeremy and Bonnie discovered Silas' tomb. Then, Katherine, who was disguised as Elena, came into the tomb to grab the cure. The only way she could do this was to awaken Silas, so, Katherine bit Jeremy, fed his blood to Silas, and then grabbed the cure before taking off. Once Silas was finished feeding on Jeremy, he snapped his neck, which killed him.
- Katherine: What is it Jeremy?
- Jeremy: I have a message from Stefan.
- Katherine: Oh?
- Jeremy: He and Damon want you to meet them at the edge of the lake by the woods. They brought the moonstone.
- Katherine: And why are you their little messenger?
- Jeremy: Because they know I'm not afraid of you.
- Katherine: Hmm, you Gilbert men, so courageous. How's John by the way? Were they able to sew his fingers back on?
- Katherine: The youngest Gilbert. This is an intriguing surprise.
- Jeremy: I’m here for the moonstone.
- Katherine: Yeah, yeah, the moonstone. It’s very popular today.
- Jeremy: Just give it to me.
- Katherine: Naïve little Gilbert. If you want it, you’re gonna have to come here and get it.
- Jeremy: This isn't going to work.
- Katherine: I think that your witchy girlfriend's worried that you've run away with your ghostly lover.
- Anna: They're looking for Mikael.
- Jeremy: Mikael!
- Katherine: Mikael. Is that his name?
- Damon: Who's Mikael?
- Anna: The vampire who hunts vampires. You don't want to wake him. He will kill all of you.
- Damon: What's she saying?
- Katherine: Hello!
- Jeremy: He's a vampire and a Hunter, and you guys would be idiots to wake him.
- Damon: Don't fall asleep, Jer. You might have a concussion.
- Jeremy: Thanks for the concern, dick.
- Katherine: Oh, stop pouting. He took one for the team. Everyone back home will thank you once Klaus is dead.
- Katherine: Come on. We gotta get you up.
- Jeremy: You have to help Bonnie. The hunter stabbed her. You have to feed her.
- Katherine: Okay. I just need to make sure that you're okay first.
- Jeremy: I'm fine. What are you doing?
- Katherine: The cure. Jeremy, after everything we've been through, it's right there.
- Jeremy: It'll be there after we help Bonnie.
- Katherine: God, I forgot what a brat you were.
- Jeremy: What?
- Katherine: I'm done playing nice. (She opens Jeremy's wrist and feeds it to Silas)
- Jeremy: Katherine.
- Katherine: It's been too long, little Gilbert. Sorry. Family reunion is gonna have to be cut short.
- Katherine was responsible for Jeremy's death.
- Even if they aren't biological siblings, they're both part of Elena Gilbert's family. Katherine is Elena's maternal ancestor and Jeremy is Elena's paternal biological cousin and adoptive brother.
- Jeremy has never commented on or acknowleged Katherine and Elena's similarities.