Protagonist
Character Role Analysis
Jacob
Jacob starts the novel, he ends the novel, and we'd be lying if we said we didn't get to know him the best throughout the book. Yes, the story also revolves around Geertrui (she's a protagonist too, for sure), but we definitely think that ultimately we only learn how her story connects to his, instead of the other way around.
Look at it this way: Jacob's got to go to Amsterdam and spend time there for the novel to even take place. It might be about war-torn love, but it's also about Jacob's search to figure out who he is. And that's what makes Jacob the protagonist.
Geertrui
Geertrui's definitely a protagonist in her own right. After all, we learn her entire life story, not just one moment of it—plus we read her memoir. So while we see what happens to Jacob from an outsider's point of view, we read exactly what happens to Geertrui during the war from her perspective. In a lot of ways, the book is her story, and Jacob is just an excuse to share it.
Check out the way she describes her time with Jacob:
I think of this as the time when Jacob and I lived together, husband and wife in all but name. We did not talk much about the future. There was little to be said except that we wanted to spend our lives together and must do whatever had to be done to make it possible. (17.4)
It's clear that this story is partly just for her to relive it and reminisce before she dies. It might have started out as a way for her to confess everything to Jacob (or Sarah), but she quickly takes over and shares intimate details about her entire life. It's this close connection with Geertrui that lands her in the protagonist camp.