Something like this. A grizzled war veteran of sorts - the cigar smoking type. Somebody that's going to curse at me and tell me "we're gonna kick alien ass" like a man. You know the ghosts have seen the same battles, if not worst scenes, for far longer... after they spent all that time alone looking for their guardians. Still though, both ghosts' voices so far have sounded like Apple products. Ron Perlman, the actor who did Hellboy in those movies and plays in Sons of Anarchy, would be a voice I would follow and enjoy doing.