剧中人局外人

As 'ju' refers to stage play, drama, opera, so this phrase combines the idea of being 'Inside Drama Outside Drama'. It means both 'person in the play, spectator out side the theatre,' or figuratively it can imply that one feels conflicted between their own personal struggles ('in') and observing others go through life situations ('outside'). It shows one has both roles within a same setting or incident.