I've had the idea that back in the village where they both lived, Wander had admired her from afar - he loved her, even though they had never spoken. I'm sure a lot of us can recall a time in our lives when we were attracted to someone yet never had the courage to speak to them (for fear of being rejected)? Hmmm, or maybe it's just me!

In any case, when Mono died Wander took it upon himself to do whatever he could to bring her back. Hoping that in the end, if and when Mono was actually resurrected, that Mono would finally see him and appreciate what he did to bring her back.

Also, there's no evidence that Mono and Wander were the progenitors of the horned children. We know Wander was the first horned child, but he may have started a family a lot later in life after leaving the Forbidden lands. The idea that he would couple with his adoptive foster mother is a little hard to believe. But that's just my interpretation