cantankerous
adjective bad-tempered, argumentative, and uncooperative

conceited
adjective excessively proud of oneself; vain

devious
adjective showing a skilful use of underhand tactics to achieve goals

frivolous
adjective not having any serious purpose or value

garrulous
adjective excessively talkative, especially on trivial matters

hostile
adjective showing or feeling opposition or dislike; unfriendly

impulsive
adjective acting or done without forethought

inconsiderate
adjective thoughtlessly causing hurt or inconvenience to others

melancholic
adjective prone to feeling or expressing pensive sadness

naive
adjective showing a lack of experience, wisdom, or judgement

overbearing
adjective unpleasantly overpowering

petulant
adjective childishly sulky or bad-tempered

pompous
adjective affectedly grand, solemn, or self-important

reticent
adjective not revealing one's thoughts or feelings readily

submissive
adjective ready to conform to the authority or will of others; meekly obedient or passive

superficial
adjective lacking depth of character or understanding

timid
adjective showing a lack of courage or confidence; easily frightened

truculent
adjective eager or quick to argue or fight; aggressively defiant