By the end of Vol. 1 Jeff Lemire dekes to the left making you think (or, at least, entertain the thought that) perhaps Jepperd isn't a main character after all, given what he does to poor Sweet Tooth. I mean the cover of the first chapter of this second volume quickly negates that idea, and logically of course Jepperd is a main character, but it does relate to the effectiveness of Lemire's writing as well as use of the strong/silent loner tropes that it could have conceivably gone either way.
With "In Captivity" Lemire fleshes out Jepped's backstory as he wrestles with his demons, while simultaneously weaving that back story with Gus' tribulations in the concentration camp he's found himself in. Its with both these through lines that Lemire brings forward more and more details on what happened to society when the affliction first hit and how it regressed thereafter. The big mystery of the series, hinted at early in Vol. 1, is explored further, that of what exactly Gus' role in the Affliction was.
Though Vol. 2 is, like the first, a brisk read it should not be construed as a criticsm or that the story is oversimplified. It's expertly crafted and utterly addictive and digestible (I went out and got the 3rd Volume today cause I needed more).