After Alaric's girlfriend, Jenna Sommers, is killed, he becomes Jeremy's and Elena's legal guardian. Their bond grows when Alaric starts living with them. Also, Alaric becomes Jeremy's part-time mentor on hunting vampires.
Alaric replaces Mr. William Tanner as the new history teacher and finds Mr. Tanner's "Jackass File", which is really just a file that is about Jeremy Gilbert. After reading the file, he offers to give Jeremy a second chance by doing an extra credit history report. He also sees Jeremy as he spends some time with Jenna Sommers.
Then, in Season 3, Alaric becomes Elena and Jeremy's guardian after Jenna died. He saves Jeremy's life after Klaus compelled him to stand in front of a speeding car.
In the episode Heart of Darkness, Alaric permanently becomes their enemy as his alter-ego starts to takes over.
In Do Not Go Gentle, Alaric makes the decision not to complete his transition into becoming a vampire. He seems to believe that he deserves this after all that he has done. Despite Jeremy's unwillingness to leave him to die, Alaric says that he has to do this. He tells Jeremy he won't be alone because Damon will stay with him. Alaric then hugs Jeremy before letting him walk away.
In The Departed, after dying, Alaric appears as his old self in the Gilbert House. When asked by Jeremy what he is doing here, Alaric says that he wanted to say goodbye and it just kind of happened. He then promises Jeremy that he will always be looking over him, and that he will never be alone. This is when Jeremy realizes that Elena and Alaric have both died and that Alaric is now a ghost.
In Black Hole Sun, Alaric takes Jeremy to the hospital after he shows up on his doorstep drunk. After taking advice from Jo, he trains with him in the woods to help him deal with Bonnie's death.
In Stay, Alaric drops Jeremy off to the bus station and gives him a bag of wooden stakes and weapons. It is revealed that Jeremy isn't attending art school, but is actually leaving town to hunt vampires. Alaric gives Jeremy information to look into while investigating recent attacks in Santa Fe. He tells him to be careful and that he'll be the first person to call when Bonnie returns. Alaric silently looks on as Jeremy boards the bus.
In I Was Feeling Epic, although Alaric and Jeremy do not interact in this episode, they are seen to be in touch again and are working in the Salvatore Boarding School together. Alaric is one of the heads of the school and Jeremy is currently a teacher there.
Alaric: [to Jeremy] You know that your old teacher had a jackass file? No joke. It's, uh, typed on a label. It has all the troublemakers in it. But really it's just an opus to you.
Alaric: I am trying to help you pull yourself together, Jeremy! Now, what is your problem?
Jeremy: My problem is that everyone thinks I shouldn't have one. I have the right to be messed up right now. Bonnie is dead! She knew it was gonna happen and she said goodbye over the phone! Just so you...
Alaric: Keep going; so what? So I can come back to life, right?
Jeremy: You, Elena, Stefan, Tyler, Enzo. She saved everybody but herself.
[Jeremy turns around]
Alaric: Listen Jeremy you want to talk about resentment huh? Is that it? My wife ran away because she would rather be a Vampire then be married to me. Come to find out it was Damon who turned her. And then she died. And then Jenna [brief pause] she died. And then the guy who killed my wife died, and I actually kind of miss him. And now, I can't even talk to a girl without fantasizing about tearing into her neck? I mean Jeremy, I have resentment for years! Years! I get it, but I find a way to keep going because that's what we do! We find a way to keep going! Okay?
Alaric: But, believe it or not you're actually an adult now. [sighs] You found your purpose, so you might as well pursue it. Grant that being a vampire hunter doesn't lend itself to a healthy social life.
Jeremy: Yeah, it turns out a social life isn't as much fun as kicking vampire ass. (He smiles)
Alaric: Just don't do anything stupid, okay? [pause] Now, I'll send you leads you can follow up on.
Jeremy: We already went over this. Don't need to worry about me, okay?
[Alaric hugs Jeremy and laughs]
Jeremy: It's not like I'm not gonna have e-mail or anything.
Alaric: Just shut up and let me hug ya. Proud of you, Jeremy.
Jeremy: Do me a favor. If Bonnie ever comes back...