Just for clarification (and curiosities sake) with all the roles taken, I assume this rp is closed?
Depends on the GM though, but you could always be a non-master/servant. A third party with your own agenda, or a member of one of the other magi's team (like on F/Z), a village inhabitant, among million other things that could greatly color the RP in my opinion, as the 'NPCs' were some of the best characters in the VN, IMO.