roles morgan le fay , king arthur 's half-sister ( soprano ) lady de hautdesert , wife of bertilak ( mezzo-soprano ) arthur , king ( tenor ) guinevere , arthur 's wife ( soprano ) a fool ( baritone ) agravain , a knight of king arthur 's court , gawain 's brother ywain , a knight of king arthur 's court , gawain 's brother gawain , a knight of king arthur 's court , ( baritone ) bishop baldwin ( countertenor ) bedevere , a knight the green knight / bertilak de hautdesert ( bass ) synopsis sir gawain and the green knight act 1 it is christmas at camelot .