Give your character some bad habits!
Negative personality traits A: abusive, accident-prone, addicted, afraid to take risks, affected, affected by peer pressure, afraid of change, afraid to take risks, aggressive, aloof, anal retentive, annoying, anti-social, anxious, argumentative, arrogant, artless, attention seeker, authoritarian, avaricious, awkward, B: backstabbing, badgering, barks orders, base, belligerent, belittling, blames everyone else, boorish, boring, bossy, bovine, brags, brutal, bully, bumbling C: callous, catty, caustic, chauvinistic, cheap, cheats, cheerless, childish, clumsy, cocky, cold, cold-hearted, combative, competitive, complacent, complainer, conceited, confrontational, confused, conniving, controlling, corrects others constantly, corrupt, covetous, coward, critical, cruel, cynic D: deceitful, defeating, delusional, demanding, denial, deranged, destructive, directed by externals, directionless, disagreeable, discourteous, dishonest, disorganized, disrespectful, dissatisfied, distant, does everything by the book, does what is convenient, doesn’t listen, doesn’t think things through, dogmatic, dominating, domineering, doubtful, dour, downer, draconian, drags people down, drama queen, drinker, drugs, dull, dysfunctional, E: easily aggravated, easily fooled, easily offended, easily threatened, egoist, embarrassing, emotionless, envious, erratic, evasive, exacting, excessive, exhibitionistic, extravagant, F: facetious, faded, false, false bravado, fanatical, fawning, fearful, feels superior to others, fickle, fidgety, finicky, finishes sentences for others, flippant, follower, foolish, forgetful, frantic, fraudulent, furtive, fussy G: gives up easily, glares often, glib, gold-digging, goody-goody, gossiper, greedy, grim, grumpy, guarded, gullible H: harasses, hard, harsh, hateful, heartless, high-handed, hogs spotlight, holier-than-thou, hostile, hot-tempered, humorous, hyper, I: ignorant, ill-behaved, ill-bred, ill-will, immature, immodest, impatient, imperious, impolite, impractical, impulsive, inactive, inarticulate, inconsiderate, inconsistent, indecisive, indifferent, indulgent, inefficient, infantile, inflexible, inhibited, insane, insecure, insensitive, insincere, inspires guilt, interrupts, irresponsible, intimidator, intolerant, irresponsible, irritable, isolated, J: jealous, jittery, judgmental, K: kept-back, killjoy, know-it-all L: lacking conscious, lack of effort, lack of self-confidence, lack of stamina, lazy, liar, life stinks attitude, lonely, low energy, lordly, loud, low drive, low self-esteem M: macho, mad, makes fun of people, makes others uneasy, malicious, manipulative, martyr attitude, materialistic, mean, meek, melodramatic, merciless, messianic, messy, misanthropic, miserable, miserly, mistrusting, monosyllabic, moody, mopey, morbid N: nagging, naïve, narcissistic, narrow-minded, naughty, needling, negative, negligent, never happy unless miserable, non engaging, noisy, nosy O: oblivious, obnoxious, one-dimensional, opinionated, ostentatious, outrageous, outspoken, overbearing, overly emotional/excitable, overly flirtatious, overly polite, overly proper, overly sensitive, overly serious, over wrought, P: panicky, paranoid, passive, pathetic, pessimist, petty, petulant, phony, pigheaded, pitiful, plotting, pompous, poor judgment, posturing, power-hungry, predatory, predictable, prejudiced, pretentious, prim, prissy, procrastinate, promiscuous, proud, prudish, puritanical, Q: quarrelsome, quixotic, quitter, quick tempered R: racist, radical, random, rash, rebellious, recalcitrant, reckless, rejects change, reluctant, remote, repressed, repulsive, reserved, rigid, rude, ruled by peer pressure, rules with an iron fist, ruthless, S: sanctimonious, sarcastic, sardonic, scathing, scatterbrained, schemer, scornful, second-guessing, secretive, sees bad in everything, self-centered, self-conscious, selfish, self-righteous, self-satisfied, self-serving, severe, sexist, shallow, shameless, shifty, short-sighted, show off, shy, short-fused, slanderer, sloppy, slovenly, small goals, smug, sneaky, snobby, social approval required, sociopathic, soft, somber, sophomoric behavior, speaks in monotone, spendthrift, spiteful, squeamish, static, stalker, starchy, stick-in-the-mud, stingy, stoic, stony-faced, stubborn, stuck up, sullen, suspicious, swaggering T: taciturn, tacky, taker, take over, talker, talks over people, tattletale, temper, temperamental, terse, thinks everyone is stupid, thin-skinned, thoughtless, timid, tiresome, touchy, trivial, troubled, two-faced, typical U: unable to relax, unappreciative, uncaring, uncompassionate, uncommitted, uncommunicative, uncooperative, uncouth, uncreative, undemonstrative, undependable, undisciplined, unethical, unexpressive, unfeeling, unfocused, unforgiving, unfriendly, ungrateful, unhappy, unhelpful, unkempt, unimaginative, unmotivated, underhanded, unorganized, unpolished, unprincipled, unproductive, unrealistic, unreceptive, unreliable, unresourceful, unresponsive, unrestrained, unruly, unscrupulous, unsmiling, unsophisticated, unsure, unsympathetic, uptight, untrustworthy, user V: vacant, vague, vain, vengeful, venomous, vindictive, violent, visionless, volatile, vulgar W: wary, wasteful, weak, wears drab clothes, weird, weary, wet blanket, whimsical, whines, willful, wily, wise-assed, wishy-washy, withdrawn, womanizing, worrier, wretched, X: Y: yellow-bellied Z: zealot