Meet Lauren's boyfriend, folks.
Well, he's Lauren's boyfriend before Bankole, anyway. And you'd kind of hardly know Curtis was Lauren's boyfriend at all from the way she writes about him. She says a few things to indicate she cares about him and his opinions, such as "I care about him more than I want to" (2.34) and "I care what he thinks of me" (2.34), but she never tells him about Earthseed or her hyperempathy syndrome.
She kind of looks at Curtis as being her option of staying in Robledo forever. "Itʼs not [an option] that I intend to exercise, but it is pretty much what the neighborhood expects of me—of anyone my age. Grow up a little more, get married, have babies" (8.6). So that's how Curtis fits into the novel: just a big fat picture of the status quo.
In Chapter 13, Curtis finally pries out of Lauren that she intends to leave Robledo and go north. She didn't even tell him. Yeah, they don't have much of a real relationship, no matter what Lauren tells herself about him. But she has good reason for hiding her emotions: her hyperempathy syndrome could be a weakness, a way for others to take advantage of her. When Curtis does let on that he's been thinking of going north, Lauren conceals her reaction and thinks: "My sharing has been a hard teacher" (13.26). She doesn't want him to know about her chief vulnerability.
That she planned to go north—without discussing it with him—obviously upsets Curtis. He asks her to marry him (13.52), but she puts him off. All he can offer is: "We could live at your house" (13.59), and: "My parents would help out with food" (13.59). Not much compared to what Bankole has later: three hundred acres.
"I have things to tell you" (13.63), Lauren thinks, regarding Curtis...but she never gets the opportunity to fill him in on her hyperempathy syndrome and her plans for Earthseed, because Robledo is destroyed first. On her way north, Lauren remembers Curtis briefly (21.98-104), but even then, his memory doesn't matter all that much to her life.