User blog comment:B214/Shin DxD 1 discussion/@comment-181.115.108.207-20180827041432/@comment-31137559-20180827144223

How can Vali be a prince? Sure he's the descendant of the original Lucifer. But Lucifer died a long time before Vali was born. And then Sirzechs became Lucifer. It would be more accurate to call Millicas a prince rather than Vali.

And Rias was the little sister of the current Lucifer so it can very much count.