Jared and Melanie are perfect for each other: Jared with his machismo and male dominance and Melanie with her good looks, athleticism, and willingness to submit to said male domination. From the very first scene they're together, when Jared realizes Melanie is human and kisses her instantly, it's clear that they're soul mates. Jared's excuse for his prelude to sexual assault: "I've just been alone so long!" (4.59).
And an overly aggressive, sexually frustrated man isn't a warning flag to Melanie, for some reason. She's in love with him, seemingly because he's "the only person left in the whole world besides Jamie and me" (8.52).
Okay, so our first impressions end up being not entirely accurate. Jared is quite a gentleman, refusing to sleep with Melanie without protection. He does protect her and will go to any length to protect her brother. And he risks his own life regularly to procure supplies for the human survivors in the cave.
His testosterone-fueled rage kind of overshadows his chivalry, however: "Melanie will always be mine. And I will always be hers" (37.128). But it seems like only the first part of this statement is true. We don't get a big picture of what Jared and Melanie's relationship is like after Wanda is out of her body, but while she's in there, Jared wants to make all her decisions for her.
We guess the best way to describe Jared is passionate. He loves hard, he plays hard, he hates hard. His truck probably has a "go big or go home" bumper sticker, and he's definitely not here to make friends. He's a great case study for Wanda (and for us) on how some people let their emotions rule their lives.
We're being hard on Jared. Without him, the cave community would have crumbled. Jared has the mad survival skills necessary to venture out into the scary real world and return, unharmed, with food and medical supplies. Also, how many times have you had to deal with a body-snatching alien taking your girlfriend? Yeah, didn't think so.
In addition to "passionate," we're going to have to add "practical." He does what it takes to get the job done. Eventually he sees how Wanda can benefit the community—by taking her out to interact with the other aliens. Ian protests, because of his need to "protect" Wanda (more on him later), but Jared knows that this is what has to be done, no matter the danger. He may be acting on his emotions, but they don't cloud his vision from seeing his ultimate goal.