That would make sense. But I always thought of the Japanese Goblin as Tengu with red face and such. And since that dad is called Rouge meaning reddish-colored in French.
So it confused me even more since I don't think that guy be capable of raping woman, so he might be adoptive dad.
I hope we get to know his past more. Then it would make more sense
Just to help you a little, yes, Rouge is Meifas adoptive father. He took Meifas in after his mom went crazy. He was village's doctor then so he tended to both her and Meifas' arm, and even got wounded protecting Meifas which made their bond strong.
***Somewhat spoilerish?***
Before, Meifas demon look really looks like a demon, Meifas tattoos are a seal to his full form. And a little off topic, Rouge hates the prince looks because he's dark and handsome like his mother's new catch, ergo, someone who stole a special person.
***Back to normal****
You can read their story in Tamago no Hi, but since I know it's shoujo (with BL undertones) and incomplete, it's not everybody's cup of tea.
Wait I thought his father was a demon that raped his mother that made her go crazy. So was he talking about his little brother that was born that time then? I'm confused. Or is Rouge his adoptive father?