User blog comment:MrAnonymous/Think Abadon will return?/@comment-3481504-20130205162046

Yes, I think we'll learn more about the Knights of Hell, hand selected by Lucifer.

Do I think Abaddon with return? Possibly. Particularly this season? No.

Personally, I think the other three could quite possibly be Alastair, Lilith and Azazel, although the are said to have been annihilated by the Archangels.