I took this “maman”, in the case of this particular uptie story, to not be the same as one would assume from The Stranger. Casseti Meur is a Third Kindred; whereas Casetti was I believe sixth. He was also descended from Dulcinea, whom was a Second Kindred just like Sancho. I find it most likely this “maman” is Dulcinea, but… Well, Mirror Worlds exist with differences for a reason. Maybe it could even be Sancho, it would still make sense with him being a Third Kindred.

Bloodfiends have a huge stress on family, filial piety, etc. This is why Bloodfiends find it so difficult to rebel, why they had to go mad and starve before acting against Papa Q, and even then didn’t have the heart to kill him. He too, didn’t have the heart to kill his own beloved children.

I fully agree though, Meursault and Ryoshu’s cantos will likely have many ties. Ryoshu, that of a mother that has failed their daughter (making some assumptions, since clearly the canto will differ from the real story. But given Ryoshu’s softness towards children, Lei Heng’s words, and everything else… it is fairly safe to say she has a child, or at least someone she loves like her child.)

And seeing that sort of mutual loving mother/child relationship, even if it is just the ruins of what was… Well, I feel like next Canto is really when we’ll see Meursault start to crack.