Jack: what a hunk. He's got that classic Han Solo charm mixed with that classic Luke Skywalker earnestness, which is the perfect recipe for tons of nerd love.
Saba is drawn to Jack from the moment they lock eyes—seriously, she risks her life to save him after two conversations—but strangely, she holds back from diving into a relationship with him. Maybe she doesn't think that a thief like him would make a good bae. Maybe she thinks that he's shady. Maybe she doesn't know how to date. Or maybe it's all three.
Despite her hesitations, Saba eventually gives in to her feelings for Jack. For starters, it helps that he proves himself to be honest, loyal, and brave far beyond her expectations. Score one. The real kicker here, however, is that Jack drops the cool guy shtick and allows Saba to look past "the Jack of the jokes an the flirtin and the shyin away" and see "the stillness at the heart of him" (9.74). Ultimately, it's this stillness that draws her in.
Jack makes a bunch of moves on Saba, but it's not until the end that Saba finally makes her own move, kissing him before the final battle. It's a shipper's dream. We'll have to check back on the sequels to see if the two of them reunite following their separate adventures.
But who are we fooling? A million hellwurms couldn't keep 'em apart.