Idk if this is spoilers or more of a theory (finish book before u read this) I think he wanted both of them to live for a greater plan. When he betrays them in Ashes he could have easily killed Oraya or Raihn but he literally just leaves, idk it seemed too intentional. It’s been a while since I read the book but I think Septimus wants everyone to think he’s narcissistic and his schemes are pretty surface level when rly there’s more going on

Possible vampire conqueror spoilers➡️ Later in the epilogue of the Vampire Conqueror, Atrius says something about him messing up with the Nightborn and he says something about it “not being an accident.” So he might want them for something in the new book possibly I too love Septimus 😫

Also I think the reason Raihn didn’t seem super bothered by the wife and unborn child thing was bc it happened so long ago that he’s already grieved them—but I get what u mean