a planetary vagabond.
a quicksilver character, cool and willful at one moment, utterly fragile the next.
a temperamental motor.
sometimes it would start and sometimes it wouldn't.
an erratic comet.
erratic behavior.
erratic winds are the bane of a sailor.
fickle weather.
his life followed a wandering course.
mercurial twists of temperament.
that beautiful but temperamental instrument the flute.