Answer: wayward

AnswerCrossword Clue
WAYWARDSteinbeck's "Bus."
WAYWARD"The ... Bus."
WAYWARDUnpredictable.
WAYWARDDisobedient
waywardwilful (bent on having one's own way, also WILLFUL, WILFULLY, WILLYARD, WILLYART)
waywardstubbornly willful