Chase Wagner might be notorious as Reno High's "storied bad boy" (As If That Weren't Enough.1), but like Brendan, his character reveals that there's often more to a person than what meets the eye. He has a negative reputation and according to Kristina:
It's not like Chase was in the running for Mr. America. He looked like a linebacker, one who didn't play much in the sun—the freckles on his cranberry skin almost pulse pain. (As If That Weren't Enough.2)
So basically, we have a pizza-faced rebel who won't be winning any beauty contests any time soon. Not exactly the kind of character you'd expect someone like Kristina to fall for, especially given Brendan and Adam's physical attractiveness. Chase might feed her drug and sex habits at first, but he ultimately has a kind heart and stands by Kristina as she deals with the aftermath of her addiction and rape.
The most interesting thing about Chase is that while he initially encourages her to get high and even gives her drug paraphernalia, he eventually realizes Kristina's totally gone off the deep end and tries to backtrack. Check out the scene where Kristina invites him to smoke crank with her after she learns that trick from Robyn: "He took a snort or two, but declined the tin foil routine," she says. "On the second refusal, I asked why not. He shrugged. I've set boundaries" (I Gave Up the Bus.4-5). Smoking meth is a whole new level, and he's not going to join Kristina there.
Okay, so that doesn't exactly explain why he opens the door for her to go insane at her birthday party on ecstasy, meth, and human blood. Don't forget, though—we're talking about teenagers, and good decision making skills aren't always a high priority, especially when drugs are involved. Our guess is that while Chase recognizes Kristina has a problem, he's not mature enough to completely give up his vices in order help her reform her life.
That's not to say that he's entirely a bad influence. When he finds out Kristina's pregnant, he offers to give up his full scholarship to film school and marry her. Even when she refuses the offer, he still insists on working two jobs while going to school in order to support her—even though he knows the child is Brendan's, not his. He also tries to talk her out of having an abortion, refusing to give her the money because he "was 'floored' by my decision" (I Needed Two Things.3).
The bottom line is that while Chase isn't exactly a savory character, he's more complicated than just being the bad boy with drug connections. We'd like to argue that witnessing Kristina's struggle actually might encourage him to step away from his bad habits for good, placing his focus instead on supporting her and the baby while succeeding at school. In that case, he's not the only person who learns a lesson from her mistakes.