So You Want To/Develop Character Personality

Principle Number One
"''When you make a character, make it/him/her human"."

All of the rest of this advice is suggestions on how to accomplish this.



The main goal of developing a character’s personality - as already stated - is to make that character human. It doesn’t necessarily mean that the character needs to be a human being or act exactly like one. Exceptions where a character has an inhuman personality can only be made interesting if human nature is understood first.

The importance of personality in a character is undeniable. Some fictional works are only considered interesting because of just one character’s personality. For example, the popular show House MD. If it wasn’t for its Main Character the show would be a generic Medical Drama. You can get a glimpse of this character’s personality by clicking here.

Furthermore, some fictional works are centered towards just one character. In fact, the personality is both the most complex and most important part of a character. A character’s personality is the main drive of most stories. It’s very likely you have heard people talking about having a “favorite character.” This character is more often than not the main reason people care about this fictional work at all.

To give an example, Jack Sparrow is the main reason Pirates of the Caribbean is successful. Disney even admitted that without "Captain Jack Sparrow" the franchise would be "dead and buried". Good characters will make people care about everything else in your story.

Avoiding Puppet characters
It’s important to note that the following advice is to help make a fully human character. It is of course possible to develop personality without following all of this advice. However before effectively breaking the rules you need to know them first, otherwise you may have a puppet-character instead of a person.

The term "puppet" is a metaphor for a character that is only an extension of the will of a writer and not a fully developed person. This means of course that literal puppet characters may be great characters too.

What is 'personality'?
Personality is defined “As a dynamic and organized set of characteristics possessed by a person that uniquely influences his or her cognition, motivations, and behaviors in various situations.” In other words your character's personality will be the behavior your character has with themselves and with others. It’s important to note that even though all people have personalities, the person isn’t his/her personality.

Interestingly, the word "personality" originates from a Latin word that means mask. This is relevant to us because it will help us to understand the concept of social masks.

First it's important to differentiate between how a character behaves with other characters (the image they give of themselves onto others) and what they really are on the inside. In Real Life people use masks to hide their real selves mainly for two reasons:


 * 1) In order to hide their inner feelings and secrets. For example the Alpha Bitch hiding the fact that she is a nerd on the inside.
 * 2) To be accepted by others. Characters can behave differently between certain people. For example The Bully may pretend to be a good person in front of a teacher.

You can apply this knowledge to characters. While many authors like to make their characters without any “masks,” this trait could certainly give more depth to your characters. Because the struggles between the outside and the inside of your character are an important part of a character’s personality, the following questions will help you to define this aspect of your character’s personality.


 * 1) How is your character when alone?
 * 2) Does your character treat everyone the same? Is your character nicer/meaner/funnier/etc. with certain people? If so, why do they act differently?
 * 3) Are the feelings your character expresses on the outside really what your character feels? For example: Is your character a Stepford Smiler?
 * 4) If your character could have unlimited power/anonymity, would your character remain the same person?
 * 5) Does your character have a burden/secrets that he/she isn’t able to share?

What makes a person the way he/she is
Identity and personality is made thanks to 3 important factors.


 * 1) Genetics. These factors are in the DNA of the person. They can’t be chosen nor changed by the person. For example, sex and age.
 * 2) Free will (Our choices). Regardless of circumstances every human being is able to choose how to guide their lives. These choices are a big factor on defining what we are. People in nearly identical circumstances can take different routes of actions. This category includes our history, past and present.
 * 3) The environment. In this category we can include all factors that influence a person but aren't directly dependent on the person itself. For example: How we interact with the people around us, how people changed our view of life, when and where we live, etc.

What makes a character feel “human”? (Human nature)
Even though the question of what makes us “human” is still a hot topic in philosophy, there are certain traits we can identify that are proper of a “developed human.” This will help a character feel human.

Autonomy.
This concept means “the capability of making decisions without coercion.” In other words, you need to remember that your characters must have their own dreams and goals. You need to portray characters as how they would act if they were real, as you want them to act, but taking into account their own goals, not as what you want them to act for the sole purpose of shaping the Plot. Unless it’s justified in the Plot, characters won’t betray their objectives nor their personalities spontaneously. That’s the difference between Character Derailment and Character Development.

For example, if your character is a Big Bad whose main goal in his life is to kill The Hero for whatever reason, if you make that character suddenly and without explanation forgive The Hero and join a ballet academy, this would be considered Character Derailment. On the contrary, if you portray The Hero redeeming the villain by understanding his Freudian Excuse and the villain gradually realizing the error in his ways, this would be Character Development.

Autonomy is also the difference between a character that is just a puppet, an extension of your will, and a person. Characters that are true people will act as they want, not as you wish they acted. If you consciously try to avoid writing a puppet character or a Mary Sue, then you are inevitably going to disagree with your character’s reasoning or actions sometimes. But that’s how a realistic character would act. This doesn’t mean that you won’t be able to control your characters. You can make your character do whatever you want without losing characterization if you take care of not betraying what makes your character autonomous.

Individuality.


All persons are unique and special. Even identical twins that share the same DNA aren’t exactly the same (regarding personality).

While this doesn’t mean that you can’t create characters that are exactly the same if your plot needs it (for example clones), it does mean however that you can’t make characters that are (in theory) different people but always or nearly always behave perfectly alike (unless it is justified by the plot), nor characters that always have exactly the same opinion or think exactly the same way. Even people that share the same goals tend to think differently on the means.

For example, two heroes want to save the world from the Big Bad, but one of the heroes wants to kill the Big Bad while the other wants to redeem him. This would be a good way to express individuality. This doesn’t mean characters can’t agree in many topics, but it does mean that the less differences characters have, the less human they will be.

Flaws (Human error).


No human is perfect and no human is always right. Your character needs flaws in order to be a person.

Ignoring the fact that the word “flaw” sounds like something “bad,” it is actually a very good thing for characterization. Characters that have the same flaws as the audience are considerably easier to identify with than their less flawed counterparts. Some flaws can make your audience identify with the struggles of your character. Other flaws will make your character unique and interesting. Making your characters outgrow some of their flaws can make interesting plot points.

However, it is important to avoid giving a character just a single flaw or fake flaws. Characters will and should always have many flaws no matter what, even if those flaws are eventually overcome or controlled through Character Development. Humans are imperfect by nature and removing this trait (with very few exceptions) will make your character feel inhuman/unreal.

A classic example of a fake flaw is being “So Beautiful It's a Curse.” While this trait appears to be a flaw, it is actually a form of Wish Fulfillment disguised as a flaw; the reason is that a desirable trait is being “masked” as something undesirable. However, it can’t be considered as a true flaw because the benefits of this trait are still present. In this case the character is still going to be considered as special and important because of his/her 'beauty.'

A perfect example of single-flaw characters is the concept of the “Fatal Flaw.” People in Real Life aren’t single-flawed. Even though it’s true that people may have a “Fatal Flaw,” people will make not just one—but many mistakes throughout his/her life, and for different reasons.

Flaws are also able to be a great source of humor. After all, not all kind of flaws need to be “big.” Other flaws can be humorous and even become a very unique trait of a character. For example, a character that always arrives late despite having Super Speed, or a rich character that always forgets his wallet.

Flaws are also what makes a character’s virtues believable. It’s very easy to give character good traits, making a perfect character even. But without flaws those virtues are not going to be believed by the audience. That’s the reason flaws are fundamental for creating a well-developed character.

There are two kinds of flaws (your character needs to have both):


 * 1) Skill flaws. Your character can’t be good at everything. Characters tend to have unique talents and interests. There are going to be things they aren’t very good at, even on things that they are skilled with. They can’t be perfect at them all the time. Characters need both strengths and weaknesses.
 * 2) Moral flaws. Your character can’t be always “right” or always “wrong.”

Your character can’t always be “the moral standard of your work.” A villain can’t be completely devoid of redeeming qualities. All people have some good and some bad in them (with few counted exceptions). How much depends on each character.

Finally, it’s important to note that both making characters defined only by his good traits or by their flaws are signs of bad characterization. For example, a villain could hate revenge, while a hero doesn’t. Part of being human is not being devoid of flaws but overcoming them. Consequentially, having moral flaws will not make a hero less admirable—on the contrary, antiheroes, heroes with flaws uncharacteristic of the archetypical hero, are more fascinating in modern fiction than heroes who have very few/no noticeable moral flaws at all.

Multi-facet ability and Unpredictability
Multi-facet ability consists of making complex, three dimensional characters that have a lot of conflicting motivations and internal conflict. This will result in more fleshed out, interesting characters. In return, this will give your character realism, conflict, and a way for your character to show many different sides of themselves. This will make the character interesting, surprising and "unpredictable."

While people tend to have a main behavior, for example The Hero is a good person and will try to do the right thing, there is a part of a character’s personality that can’t be predicted. While the goals of a character should always be predictable (unless they are hidden from the audience), the way those goals are accomplished shouldn’t be set in stone.

The reason they can catch you by surprise is because it's very difficult to completely know a person. Just like a person in Real Life your audience will get to know your characters more as the story unfolds. It's for this reason in most stories you aren't going to know the character well enough to predict with accuracy what they will do in every new situation.

If the situation is new, then the audience won't necessarily have enough experience or knowledge with the character to guess what they will do in this new situation. It really isn't about making a character do new things, it's about the character confronting new things and growing from them, which will then change them to the point that Character Development occurs.

Interesting characters tend to be multifaceted, because then the reader will not know what they are going to do before they do it. One way to give the personality depth is to show different sides of themselves but being careful of being consistent in order for the character to be believable. For example:


 * 1) Contradiction between what the characters say and what they do.
 * 2) Contradiction between treatments of different people the character knows, like how a working man who is a father seems to have a completely different personality depending on who he is talking to: his child or his colleague. A character's varied treatment of different people is a good way of showing different portions of their personality.
 * 3) Making your character face situations that he/she has never experienced before. For example, marriage.

It’s important to take care of not making your characters predictable. If the audience knows (literally all the time) what a certain character is going to say or do, then the character just has a role disguised as a personality. However it's important to note that consistency and being multifaceted aren't mutually exclusive. The former is what makes the character unique, their "essence," while the latter is how the character's goals are accomplished.

On the other hand, you can't make a character unpredictable for the sake of being unpredictable. Worse still is an Out-of-Character Moment, in which a character whose personality has already been established momentarily does something that completely contradicts their motives and character traits for no apparent reason. For instance, an army sergeant who is rational, follows rules, and devoted to the greater good suddenly decides to risk the lives of his whole squad and break protocol to save one of his wounded soldiers rather than save a group of nearby civilians from some threat. Unpredictable? Definitely. Good writing? Not really. Unpredictability is interesting, but inconsistency is annoying.

There is nothing wrong with a story or a character that is predictable. It's all been done before. What makes a character great is how well you get your audience emotionally involved with the character. Even when they see the Heroic Sacrifice miles off and realize it's coming from page one, the emotional roller coaster ride getting there will have been worth it.

Goals and dreams
"For where your treasure is, there your heart will be also."

- Matthew 6:21



All humans have dreams and desires. It doesn’t matter how “gifted” or “rich” a person is. Characters need to have goals; both in short and long term. Goals can be as simple as wanting a sandwich or as complex as wanting to save the world. Their motivations are very important factors linked to personality. All people desire things (even omnipotent characters tend to desire being able to desire something). These goals will be very important in order to define a character’s personality.


 * 1) What is your character's greatest desire?.
 * 2) How much would that character give to accomplish it?
 * 3) Who does your character love? (friends, family, lovers etc.)
 * 4) What does your character enjoy to do in his/her spare time?
 * 5) What are your character's hobbies/interests/likes/dislikes?

Mutability
""Life has got a habit of not standing hitched. You got to ride it like you find it. You got to change with it. If a day goes by that don't change some of your old notions for new ones, that is just about like trying to milk a dead cow.""

- Woodie Guthrie

People change by various factors. The most important of them is time. Characters that never learn from their mistakes nor mature are devoid of an important part of the character’s humanity. While this trait is often ignored in order to preserve the status quo, mutability isn’t an essential human trait for a fictional story. Furthermore, some fictional works could be hurt by having mutability. Mutability is still an excellent way to develop a character, however it isn’t a synonym of improvement. Mutability may include the Start of Darkness of a character.

People's personalities always develop. In children and teenagers at great speed, in young adults at a moderate speed, in adults rather slowly, and in elders even slower unless dedication and special effort is put into it. Especially when writing young characters, their personalities should develop, and take influence from what is happening around them in the story. This makes not only for good realism but also adds depth and interest to the characters.

Inspiration
It’s important to remember that Real Life is the source of all art. Real people are the most important source of personality there is. Quite possibly you have seen/met people in Real Life that could be a good source of inspiration. Real Life has an infinite source of unique personalities that you can be inspired from. Knowing psychology is also a good starting point to define character’s personality. Even basic studies in psychology could help a lot to get the logic behind very different personalities (even "insane") to write them.

Theme characterization is also a very common and a very good source of inspiration. However it’s important to take care when you design a character to not define a person solely by a role (The Smart Guy, The Hero, Big Bad etc.) or a theme (Shrinking Violet, The Smart Guy, Yandere etc.). While getting inspired by a certain trait may be a good starting point, a person’s personality is more complex than can be solely defined by one thing. For example if you want to make a Tsundere character, you need to make a person that also happens to be a Tsundere, not a Tsundere that also happens to be a person.

Developing the personality
There are a lot of adjectives that describe characters, in particular personality and behaviors. It is important to think about how strong these traits are and how strongly they affect the character's personality. Is the character very abrasive or just somewhat abrasive?

How big of an emotional spectrum does the character have? How are these emotions expressed? When are they expressed? The bigger the spectrum is and the more detailed the answers to the other two questions are, the more complex the character tends to get. What is the character's default emotion?

Backstory
Backstory can be a great way to expand a character's personality—as well as explaining how they became what they are—but you have to make sure it meshes with their personality. After all, a character who was beaten and left for dead as people simply walked by probably isn't going to be the most idealistic person (without a good reason). On the opposite side, a person who has largely dealt with society's good side will be more likely to be an idealist.

Self-esteem and self-concept


How much does your character love/appreciate themselves? What is the perception your character has of him/herself? This perception your character has of him/herself is going to dictate greatly how your character behaves.

A character who acts arrogantly does not necessarily have a good concept of him/herself. As we discussed before, a character may try to hide self-loathing and insecurities behind a false mask of security. For instance the Stepford Smiler, or the fake stoic.

Narcissism isn't a synonym of "super high" self-esteem either. On the contrary, it’s a sign of a low self-esteem. People with high self-esteem accept themselves unconditionally, accepting realistically both their defects and their flaws. On the opposite side, a narcissist, instead of accepting him/herself just the way they are, try to exaggerate their own virtues in order to feel better with their own selves.

Depending on the level of self-confidence your character will have we can classify various levels using Nathaniel Branden’s scale


 * With high self-esteem, your character will feel “confident” and “capable”, “worthy” and right as a person. They firmly believe in their ideals, trust their own judgment, don’t feel guilty when others disagree with their judgment or ideals, trust in their own capabilities (but may ask for help when needed), and they consider themselves as valuable as everyone else (not superior or inferior, just different).
 * Low self-esteem corresponds to feeling wrong as a person. Characters with low self-esteem tend to change by various factors, for instance: Heavy self-criticism, inability to accept criticism, indecisiveness (fear), excessive will to please, inability to say no, perfectionism, guilt of mistakes (exaggerates the magnitude of mistakes or offenses and complains about them indefinitely), floating hostility (irritability always on the verge of exploding even for unimportant things), pessimism, and a general lack of will to enjoy life.

While your character's own self esteem will be defined by you as an author, it’s important to take care of your character’s background, because it will be the reason your character has their current self-esteem. For instance a character with Abusive Parents is very likely to have a very low self-esteem.

The best way to change a character’s self-esteem is gradually through Character Development. For example while revealing a character that was believed to have a high self-esteem as being self-loathing all along (or vice-versa) isn’t uncommon and may in fact be a good way to give your character Hidden Depths, portraying a character that “instantly” changes their self-esteem is unrealistic.

Mechanisms Of Defense
Defense mechanisms are unconscious (this means that your character won’t be aware of them) psychological strategies people use to cope with reality and to maintain self-image. These mechanics are normal for any person.

For this reason knowing is a great way to give your character’s personality depth. Psychological defense mechanisms are an overlooked aspect in personality that are a major point in continuity and depth of a character. Try it: pick a favorite character, identify their most important defenses, and now change them. Are they still the same person?

These parts of the personality are as overlooked as they are essential. They are best expressed by showing and not telling. Just like emotions they can be great tools to show how a character feels about a situation without directly implying it.

Using a popular example from media, Spider-Man is a superhero that is famous for making fun of his enemies while fighting. What some people don't know is that he does this because he tries to hide his fear. The mechanism of defense used here is humor. As you may have already noted, this is a good way to give depth to personality without emotions.

Personality disorders
Personality disorders are behaviors that makes adjusting to life difficult. Since lots of people do this it's important to recognize that everybody has these traits to one degree or another. When they don't cause problems they're called personality styles.

While it's an important part of personality, the topic is too big to be exposed here. To learn more of this topic in depth the following reading is recommended.


 * 1) Hollywood Personality Disorders analyses personality disorders as they appear in media.
 * 2) Wikipedia's article on the subject.

However it's important to note that personality disorders aren't a necessary or obligatory part of good characterization. On the contrary they are only recommended for characters that are designed for this purpose. But if used correctly they can make very interesting characters as well. If you want to create a character with this issue this guide will still be a good complement.

Personality types.




One of the most common divisions of personality is between extroversion and introversion. By reading this you may be wondering, "what's 'better', introversion or extroversion?" Neither, of course. It is often wrongfully assumed that extroversion is "good" while introversion is "bad." They are simply different and neither of them is superior. Both are able to develop very interesting, complex characters.

It's important to note that no person is 100% introverted nor extroverted. All people have moments of both. What needs to be defined is how much.

If a character is most of the time “extroverted,” that character will be considered as "extroverted." The same will happen with introversion. Now we are going to see the most common traits of each one:


 * Extroversion. These kind of characters are mostly identified by their happy and positive dispositions; they enjoy being around people. On the contrary, being alone is very unpleasant for them. This kind of character can be best described as "enthusiastic," "talkative," "assertive," and "sociable."They are hardly ever seen alone or without a smile.
 * Common character types that are extroverted: Genki Girl, The Pollyanna, Tsundere, The Ditz, etc.


 * Introversion. They are mostly identified in a story by being very "reserved", "serious", "mysterious", "not very social", and "solitary." Introverts spend most of their time through reflection and solitary activities (in fact they feel more comfortable when alone). They prefer to concentrate on a single activity at a time and like to observe situations before they participate. They are more reserved and less outspoken in large groups. Being able to trust their companions is very important to them. Because of that they tend to be more "selective" when choosing their friends.
 * Examples of common character types that are introverted: Shrinking Violet, The Stoic, Emotionless Girl, Uncanny Valley Girl, Dandere, etc.

It's important to note that a shy or lonely character isn't necessarily introverted. An introvert is alone by choice, whereas shy and lonely people are alone because of fear. However, both introversion and shyness may overlap. It's also important to remember the fact that it's impossible for a human being to stand completely on their own. All humans need the love of others.

Another thing to keep in mind is that extroversion does not necessarily refer to how positive a temperament a character has, only how much they enjoy other people's company. A positive temperament is covered under low neuroticism. See: The Big 5 (another theory of personality).

How is personality expressed? (Externally)


A character’s personality is expressed mainly through their external behavior.

This part of the personality is how a character expresses his or her feelings to the people around them. They aren’t necessarily the same feelings the character has on the inside. It should be noted that unless a character isn’t human or is affected by the plot, they must experience the full array of emotions. Whether or not those emotions are expressed will depend on how you develop your character.
 * 1) Expressions/Reactions
 * Facial expressions
 * Body Language
 * Movement
 * Gestures
 * Poses
 * 1) Manner of speech
 * 2) Habits
 * 3) Cultural tendencies

Characters may also express their personalities indirectly through their appearance, their possessions, their living spaces etc. It might help flesh out a character's personality if you describe their home or workplace, and how their habits affect it.

How is personality expressed? (Internal)
In order to make a complete character trivial and general information is important as well, like:
 * Likes and dislikes
 * Interests? What qualities endear the character to the subject?
 * Hobbies? What qualities endear the character to the hobby?


 * Is the character dynamic or static? Does the personality have room for change?
 * Good characters struggle, learn and grow, which affect their personality.


 * What are the characters short/long term motivation/goals/desire/temptations?


 * Does the character struggle with inner/outer conflict?
 * Inner conflict: An inner war between incompatible choices, about subjects like ideas, morals, needs, values, desires, and interest. They may be actual oppositions or just perceived as such.
 * Outer conflict: An outer war between characters, society, nature, technology, and destiny.

Showing how a character interacts is a good way of showing different portions of their personality.


 * The emotions, thoughts and actions the character has need to harmonize and reinforce one another.
 * What are the character's fears/regrets/doubts/ethics?
 * Characterization through appearance can be important because they may reinforce the character's personality, like choice of attire and hairdo.

Sex based differences


An interesting character will be interesting regardless of sex. Take your favorite character and change his/her sex. Is that character still with an interesting personality? As you may note a character’s depth isn’t going to depend on sex at all.

The issue of sex differences on personality is still a hot topic in psychology and in biology. Which personality traits (if any) are exclusive of female and male people is still a source of debate. However it can be safely assumed that physical differences between sexes are biological in nature and not psychological. Generally there's more variance within the sex itself than the patterns between them. People are people, first and foremost.

Most differences that are perceived between men and women are social in nature. In other words the society is going to decide what is acceptable for a male or a female to do. For example the stereotype of pink being a female only color wasn’t true in the 19th century, where it was considered a male only color. What a society perceives will depend directly on the time and place that society is placed.

In order to understand how a character’s personality will be affected by gender roles, you need to take into account the 3 things we spoke before.


 * 1) (Environment) The rules and expectations the society were your character resides has for each gender
 * 2) (Free-will) How much does your character follow the rules of that society? Does your character defy or follow what society expects of him/her? And how much to they follow/defy them?

Regardless of what is considered as "feminine" or "masculine" in each society, it's expected that most people will try to become accepted in that society and consequentially must/will follow those social expectations (regardless if they agree on them or not). For instance in our western society a female that behaves as male will be considered a Tomboy while a male that does the same is considered a "sissy." Contrary to popular belief, this behavior isn't directly related to sexual preferences. Your job will be to define how much your character embraces their own gender expectations and how true those expectations are to their personalities.

Realistic Female Characters
"Girly doesn’t automatically equal stupid. Girlyness doesn’t make a show bad, bad writing does."

- Lauren Faust, creator of My Little Pony Friendship Is Magic



The main issue when creating female characters is that they are, most of the time, defined by a stereotype or a role instead of a personality. When women are the protagonists of a story they a typicality or how people wished women acted. Typically they have the roles of a typical girlfriend, Mom, “Token Girl” or sex symbol. In other words they are defined by what society expects of them instead of having a true personality.

While it is true that some female characters will try to be what society expects of them, defining women solely by what society expects of them is a big mistake. Even women that do also have unique goals, desires and interests. One of the most common mistakes while portraying female characters is that they are depicted as an “army of cookie-cutter nice-girls or cookie-cutter beauty queens”.

Girls are complex human beings (just as guys are). They have access to all the attributes (virtues, flaws) men do; beyond social rules and expectations, creating a female character is the same as creating a male one.

When you portray women in a story there should be a diversity of personalities, ambitions, talents, strengths and even flaws. Don’t be afraid to portray any of these to diversify them. Regarding personality there isn’t a “male or female only” assortment of traits, while inside a story and in Real Life society won’t accept some of them.

It’s your job to define how much your female characters are going to embrace their dreams, goals, interests and how being (or not being) true to their own selves will affect the treatment they get by others and of much their personalities are defined by them.

Non-human and cartoon characters.
These kinds of characters are the exception of the rules. After you have understood what makes a character human, you will be able to make inhuman characters.

Once you know what makes a character "human" you will be able to portray inhuman and cartoonish characters. Basically these characters tend to break some of the rules we have mentioned before. For example an alien that doesn't portray emotions is going to be considered "alien" because we humans tend to be very expressive with a very wide and complex array of emotion. When you are portraying an inhuman character try to consciously "bend" or even ignore the rules of human nature. This will give you an interesting variation of characteristics.

Don't forget to take into account that inhuman character's culture and ask yourself how his/her past beliefs affect their current perception of our culture. For instance if your character comes from a planet where females don't exist, how would he react to our culture?

On the other hand cartoonish characters mostly break the mutability and predictability rules and sometimes individuality. Knowing the rules is the key to break them effectively.

A person's culture is not the only defining aspect of their character, and even if there are actual physical reasons for the "hat"—say, it's related to their species' evolution somehow—that doesn't mean every character needs to be totally dominated by one trait. After all, while some aspects of human personality relate to our own evolutionary history, by no means are humans a Planet of Hats. Developing an alien species without resorting to giving them a hat may be more difficult, but it's also much more realistic and interesting.

Potential pitfalls

 * Be wary of 'theme' characterization. Once you know who your character is in broad strokes, it can be tempting to try to make everything about them match their personality perfectly—their clothes, their interests, their employment history, everything. Real people are sometimes interested in things you'd never guess simply because someone else got them into it.
 * Real people sometimes dress in ways that are not typical of their personality. Real people don't have bedrooms that accurately represent a cross section of their interests unless they have the money to do so and an interest in shopping and decorating. Even people with awesome taste will like a few things that are tacky. Even a person who despises whimsy may bake cupcakes for a living, if that's the job that was available when they happened to be broke.
 * If you're filling out one of those long lists of questions about your character and find your answers all match a few basic elements of the character's personality, rethink; characters feel more real when they seem like they've had a mixture of experiences that shaped them majorly, not experiences that shaped them very little and experiences that really didn't shape them at all.
 * It is important that theme characterization isn’t a pitfall when it is caused by technical issues. For example, anime characters' rooms are often devoid of anything personal (I have read that this is because of budget restrictions) and they often all wear the same school uniforms; at least some characterization of this sort does not hurt.