what roll does the messenger play here?

The Messenger is the first character to appear. The Messenger has no role within the story of the play itself, but simply speaks the prologue outlining what the play will be like. The messenger tells the audience to look well and "take good heed" of what in the play. There is a moral here that the messanger wants the viewer to take to heart. That's really all the messanger does.

Source(s): http://www.gradesaver.com/everyman-and-other-miracle-and-morality-plays/study-guide/character-list/