Its a fair remark, but I don't really see how else they can be. They have no memories, no identities beyond their bond with each other and their skills, no tribe. Nobody is willing to offer both of them at the same time true friendship.
Doesn't necessarily make them more lovable characters, but its a perfectly natural state of affairs.
It is very understandble. They have no past only each other, no childhood, parents or friends. I have my own theories about who or what they are, only time will tell me if I'm right.
Kind of funny, that. The people who have no identity, no self, are the ones who must be self-centered. Which means that our sense of self comes from what we are to others. There's something quite profound in that.
Since my teen years, I've been aware of the fact that people have different identities with different people -- you aren't the same person with your parents that you are with your friends, or with your parents' friends, or with extended family. And in my case, I had diverse friends who didn't care for each other, and I was different depending on which ones I was with. Yet I was still very much the same person. It was a matter of which experiences, which language (dirty or not -- it wasn't a choice of foreign ones, except what French I had from classes), which shared jokes and mutual companionship were on the surface of the interaction. So we're really like a Venn diagram circle, and our identity is the intersection with the circle of whatever people we're currently with -- and Cass and Orc don't have shared intersections with anyone else to a degree that means anything, so all they are is what they are to themselves and each other. And whatever intersection is forced upon them by others who want to use them, such as Daroguerre.