Well, Sphener still serves Junil, even though he's fallen as far as the Compact is concerned. Surely, Hyborem wouldn't balk at using a similar loophole, if it was to his advantage.
Also, Hyborem never belonged to Agares the same way other archangels belonged to their gods. Hyborem wasn't created ex nihilo to represent his god's sphere, and Agares seems to encourage competition amongst his minions, rather than appointing Hyborem any special position or privilege. Further, he was created from the twisted reflection of Cernunnos as he attacked Agares, acting against the orders of Sucellus and without his ara. Is it possible that Hyborem never had Agares' ara at all?
