So, he already knows that the baby is not his? Well if its like that he's dumb-
Nope, he only thinks that navier is infertile
Nope he is a giant idiot who think Navier is infertile after all his mistress is having "his baby" (but we all know that it's not his). Later I think he figures out the Navier isn't infertile but I don't know if he ever figures out that he ain't the father. I find it all comical, it's so ironic that he is an ass and he is the one who is infertile (I usually wouldn't laugh about this type of matter because it can be heart breaking for couples, but this time I can't help be cackle)
Its really funny to think the emperor is the one actually infertile and a faceslapping situation is navier will give birth to twins hahahahjaja. Hahahahahhow you like that