Bankole is one of a May-December romance right at the heart of Parable of the Sower.
Yeah, this dude is Lauren's 57-year-old cuddle muffin.
Bankole enters the story on August 27, 2027, pushing a saddlebagged cart of supplies (19.24). He's just a year older than Reverend Olamina (19.33), which kind of makes him a father figure for Lauren, whose religion doesn't even have a father figure in it. (She's got to have a father figure somewhere, right?)
Anyway, Bankole seems to come from some degree of money, since he doesn't "look like a man who scavenged" (19.24) and has clothes that "fit him well" (19.24), as well as other good stuff, including "an expensive professional haircut" (19.24). He's also got this good-lookin' beard that he's kind of vain about combing (23.30).
As Lauren eventually figures out (21.63), Bankole is a doctor—a family practice doctor, in fact (21.64). That makes him a good match for Lauren, since she's got a medical condition, that old hyperempathy syndrome. Like Lauren's hometown of Robledo, Bankole's home community was destroyed by fire and scavengers (21.51). That's why he's headed north. He almost left when his wife, Sharon, died, but stuck around since people were taking care of him (21.43-45).
Bankole is happy to join up with Lauren's growing Earthseed group because they share his concern for the wellbeing of strangers. Initially, that's Jill and Allie, whom Bankole helps Lauren save from the earthquake rubble in Chapter 19. As Bankole puts it, he is "surprised to see the anyone else cared what happened to a couple of strangers" (19.132). He even very formally asks permission to join Lauren's group—"If you don't mind, I'd like to travel with your group" (19.134)—and is welcomed by her.
Bankole and Lauren end up having sex, which allows Lauren to benefit from her hyperempathy syndrome for once instead of just suffering from it. Lauren is cautious about opening up to Bankole, though. She wants to be assured he won't laugh at Earthseed, and that he'll still accept her after learning about her hyperempathy syndrome. He finds the syndrome interesting (22.91), but is pretty wary of the Earthseed. He even calls Earthseed his "rival" (22.49)—but he tolerates it enough for Lauren to accept his offer of letting her clan settle on his land.
Yeah, Bankole's got some serious acreage going on here—three hundred acres of land, to be precise (22.15-43). That's property that can be of use to Lauren. It may be kind of un-romantic to see him in such terms, but Lauren and her group are really focused on survival and can't afford to just turn stuff down. Before accepting his land, of course, Lauren does quiz Bankole on whether he accepts Earthseed and her hyperempathy, and he does pass the tests. But something feels not quite right about it all. Check out the novel's sequel, Parable of the Talents, for more.
All in all, it seems Bankole does share Lauren's concerns for others, and he is highly motivated to win over our narrator—even to marry her (22.76-78). But in many ways, like Lauren's father, or like the impersonal God of Change, Bankole is a mystery man, not someone entirely transparent to Lauren or to us.
Of course, even Bankole's father, according to Bankole himself, "had to be different" for "all his life" (19.31), so maybe being mysterious just runs in families.