Revoke title from your direct vassal, hand out to Zealous Cruel substitute. God will do the rest.
Seriously, how is this any different to starting as the ERE in the 769 start ? Apart from this time being Miaphysites rather than Iconoclasts it sounds almost identical to me.
I say RP the hell out it - go with the flow, try and manage a cosmopolitan realm or go medieval on some assess and start cracking heads.
Some day someone will write a book about your exploits !