Let's start with the obvious: Mothers and Daughters consists of four volumes, each with its own title.
Each of these volumes presents a voice engaging in philosophical discourse that goes beyond commenting on the action at hand into analyzing life, the universe, and everything, as Douglas Adams put it.
In the first volume, Flight, the voice is that of Suenteus Po, speaking to Cerebus, although as we shall see one can make the argument that Po is to some extent Dave Sim's mouthpiece, and that Dave is addressing the reader more-or-less directly through Po's discourses to Cerebus.
In the second volume, Women, we have the facing text pages containing extracts from the works of Cirin and Astoria. In this case, any temptation to see either or both of these figures as representing Dave's point of view will be pretty thoroughly exploded by the end of the next volume. Still, it's worth noting ere that the "Cirin" who authored The New Matriarchy, for instance, is probably the *real* Cirin, not Serna/Cirin the usurper. While it may seem inconsistent with his view of women in general, by creating the plot that he did and presenting her to us the way he does, Dave actually seems to have some sympathy with and give some credence to the original Cirin. And while nothing could be farther away from the good and the true, in Dave Sim's mind, than modern feminism and by extension the Kevillism he has said is the Estarcion analogy to it, the character of Astoria, as presented in Women, ends up on a par with Po as one of the most enlightened characters in the entire saga.
The third volume, Reads, has the extended discourse from Viktor Davis that has made "misogyny" an unavoidable word in any serious discussion of Dave Sim -- if you don't use it to describe him, you really have to explain why not, or you're not really being serious.
The final volume, Minds, again has a character ostensibly addressing Cerebus but also speaking directly through the character to the reader, and this time there's no question that the character is Dave's mouthpiece, since the character is, indeed, "Dave," Cerebus' creator.
The extent to which we weigh the relative value or merit of each voice's observations and arguments goes a long way toward deciding which bit of information is reliable, which viewpoint is trustworthy, which conclusion we can be certain Dave Sim shares and wants to get across to the reader.
It's pretty obvious that the Cirinist/Kevillist tracts are not meant to be taken by the reader at face value. They represent, as Dave would now say, the voice of YHWH, or two separate voices of YHWH arguing with herself, splitting and splitting and splitting again in the manner Victor Reid would analyze in Reads (although Victor saw it as an inevitable consequence of Kevillism per se, while Dave would argue that it's a consequence of the feminine mentality). On the other hand, we can assume that these are what Dave Sim considers to be accurate summations of the viewpoints he identifies as Cirinist and Kevillist. What other insight we may be able to glean from them is problematic.
Some readers will find fault with presentation of Po as a spokes-voice for Dave, since Po clearly argues in Reads that there is both a God and a Goddess and seems to be implying that they are equal, a point of view that seems strenuously at odds with Viktor Davis' observations later in the same book. On the other hand, there are many clues that Po is a privileged character, presented to us as one who is superlatively wise, knowledgeable, and trustworthy.
Finally, there are the two different versions of Dave himself, one of whom tells us that the mask of a separate identity with a fictional name is a fundamental necessity, while the other speaks directly to Cerebus with his real name. Is one of these more "real," more truly representative of Dave Sim than the other? Oddly enough, I'll argue that, while both are obviously fictional constructs containing only limited aspects of Dave Sim's real personality, "Viktor Davis" is, by way of being a fuller and more detailed creation, more Dave than "Dave" is.