Maybe they use a normal way. Lol...coz she got only one son. Or that is just one from many methods to have a child. And to consume magic dose need more hundred years to consume, maybe he prepared it. Like his mom, not. Just theory.... however this is all fantasy so any logical thing does not apply in this manga. Hehehe....
Ah, but if they had one son, and the human man died before they could have another, isn't that what happened? They probably tdid not have it the normal way just cause of the flashbacks of the man and queen from the demon lord (child ver) perspective. They didn't seem to have "that" sort of relationship. Also, how old o you think the human man was? And the demon queen is upset that the humans killed her summoned husbando right? Anyways, ye to the fantasy world. It doesn't have to make sense xD ╮( ̄▽ ̄)╭
Yeah...maybe u are right about the relationship between the two but th Demon Lord also said that ongoing to raise him, the three of them can live like a real family he had now. So the relationship might be not so bad. I agree u said they conceive the child not in normal way. But Like I said early, the issue about the magic dose maybe is the one of hundreds method to get a child but not use by his mother. The triggered the demon queen rampage maybe coz her husband died.
I have a question plz don't hate Me but if make a baby by let the human drink some magic dose that mean the demon lord's father was the one to drink it to bear child or What???