History:

Black Moon Manga Series (for convenience sake)
She arrived from the sky with a pistol demanding the Maboroshi no Ginzuishou. No one knew who she was, and what she was there for. She basically bullied her way into the Tsukino household which made Usagi furious. (Usagi had enough troubles with all but Sailor Venus and Tuxedo Mask gone). But soon Usagi, Minako, and Mamoru found out that she was from the future. They also comforted her and found that she wasn't as much of a brat as she seemed, and was more of a scared child who didn't know how to express her feelings. (After all she had people chasing her and terrorizing her). They found out that she'd been trapped in that Chibi body for 900 years! Her father had turned into a hologram (ala Queen Selenity), and her mother was trapped in crystal. Most of all she blamed the entire thing on herself. In the end she learned about friendship (after being jolted out of being Black Lady by Pluto's death) and what it really meant to have a friend. Then she became a Sailor soldier.

Infinity Manga (for convenience sake)
We start to see Chibiusa's heart develop. With her parents safe she doesn't have to worry, and starts to open up and develop as a person. You can see her heart start to show when she doesn't care that Hotaru is a cyborg (manga only by the way) and that Hotaru is her friend no matter what Hotaru is, or does. She even sacrifices her Heart Crystal to Hotaru. She might seem a bit naive in this, but you begin to see that she really cares. She even made a true attempt of bringing Usagi and Mamoru together, not because she wants to be born, but because she truly cares for them! (see Takeuchi-sensei's notes)

The Dream Manga (for convenience sake)
We see Chibiusa develop even more as a character. We get into her mind. She isn't a mysterious precocious brat anymore. She's still precocious, but she suddenly has a full heart. She will sacrifice herself for her friends. She has hopes and dreams, and finally realizes that Mamo-chan is an impossible dream. She finally realizes that she can find her own dream and starts living outside of her Mother's shadow. In fact by the end of the story arc she is called Princess Lady Selenity (though in the future she's called Small Lady still.. O_o;) She finds her Prince (Elios) and she has become a soldier in her own right with the advent of the Pink Moon Crystal. She also gets her own soldiers Sailor Vesta, Sailor Ceres, Sailor Juno, and Sailor Pallas. Then she finally returns to the future.

The Stars Manga (for convenience sake)
She saves the day with the Sailor Quartet. (Pink Ladies Freezing!! Kiss!!) She's fully grown and there to help Usagi. She works with Usagi and actually plays somewhat of an important role once she shows up. If she didn't show up the information about there being one Moon family child would have never been revealed. (and you couldn't have seen that really cool face she made when the suggestion that Chibichibi was her sister and then her child..) You also start to see some of the mothering aspects of Cancer when she reacts to Chibichibi. (It's really cute!) "Chibichibi, you know about this battle, don't you. If you really are my little sister, then our future must exist. We win this battle, and save everyone, don't we!? So that's why you told me to believe in Sailor Moon, right!? Chibichibi, who are you really?" (translated by Alex Glover!)

Anime:
A few facts in the anime changed about Chibiusa. Such as the emphasis on her fear of lightening (which is there in the manga, but only because it reminds her of the attack on Crystal Tokyo, and therefore her guilt associated with it). She did draw a pistol on Usagi which started their relationship. Usagi noted that Chibiusa was a lot like her when she was her age. Also the time that Chibiusa came back in the SMS arc was different than in the manga. She never left originally! The emphasis on the relationship with Usagi was messed around with. They also changed how Chibiusa became a Sailor Soldier and how Black Lady was changed back into Small Lady. Overall there wasn't much of a drastic change that would really effect her personality. One thing that might change most people's perception is that she really didn't start to love Elios until she found out that he was human! (also He's cursed in the manga and doesn't have that horn when he's not under the curse). She never came back for main storyline of SM Sailorstars (She was in Sailorstars, but only for the first 7 episodes). Overall basic history of the character was not messed with much. (though I have several votes that the Amazoness Quartet not becoming Sailor senshi was a huge waste!)

Personality:

Manga:
Why do you think Chibiusa starts off as a brat? She's forbidden to see the only friend that she has (Sailor Pluto, to her Puu). She has people chasing her, her mother is caught in crystal, kids her own age are making fun of her when she wants friends (as you find in a Cancer), her father is a hologram, the senshi are stuck protecting the palace, and most of all she blames the entire thing on herself. She feels that at this rate she will never become a lady. She also feels that she can't tell anyone. She doesn't even tell Pluto that she used the time gate (with the King's permission). Most of all everyone is calling her a midget. (which is a closer meaning of Chibi) which is the exact opposite of what she wants to be!

But when you take a closer look and step out of her archetype: a precocious little brat with a rubber floating ball (a crybaby is an archetype too!). You can see qualities that you don't find in any other characters.

In many ways she is like Usagi. She makes friends easily (once she learned to open up), she will sacrifice herself. She has mothering qualities to her. She cares very deeply for the friends around her. She makes friends with outcasts. She's popular (In the Dream manga she became the President of her class!) and well-liked. She's beautiful (many boys ask her out). If you give her a chance she will open up and immediately become your friend. But she also has many qualities Usagi doesn't have.

Her dream to become a Beautiful Lady like her mother often rules over her behavior. In this way she tries to be more mature than she is. (which is why she is so precocious). She strives for personal perfection most of the time, and tries to be academically strong. She's much more coordinated than Usagi (with Neo-Queen Selenity as an example) and isn't as nearly lazy as Usagi. She takes the time to actually do things (which is why her grades are better) She also sees helping others as part of attaining her dream. She's more eager to go to battle than Usagi is. (she also wants to become a great Sailor solider). She's always ready to battle, even if her attacks are weak and pathetic.

In the same way her dream works against her. Because of her dream she doesn't open that easily, because sometimes she feels she has to do everything alone. I think she perceives that this is what adults are supposed to do. She thinks that adults can do everything for themselves. Therefore she doesn't ask for help when she often needs it. (though she did ask for it once off of Mamoru and Usagi in the Infinity manga to make them happy again and get them back together) She keeps a lot bottled up inside her and sometimes has a hard time expressing herself. Mamoru is the only one she really feels comfortable opening up to, because he's familiar, and Usagi to her is more of a sister. Mamoru is essentially a mentor. Later she also begins to trust Elios and open up to him.

She does develop as the story goes on and she does begin to trust not only more people, but the people she already knows with more of her feelings. She also learns that growing up quickly will not make her dream come true, it's time that will make her dream come true. She still strives to become a real lady, but not as hard as she used to before. She also learns to trust in herself and her friends more and ask for help when she needs it.

Anime:
The anime chose to make her more of a brat, and also cut various character development that you can see in the manga, but not in the anime. Though on occasion with various episodes they did take the time to develop her most of the development is not there. Changes were made, such as more fighting between Chibiusa and Usagi. But also in the same respect they chose to make Chibiusa and Usagi's bond different than in the manga. It was more of a sister relationship and a relationship found in arguments.

She fights with Usagi because Usagi reminds Chibiusa of herself and what she exactly doesn't want to be. She is more academically strong and very popular. To her Usagi is her sister, and Neo-Queen Selenity is her mother. (Neo-Queen Selenity even called Usagi, Chibiusa's sister) To her the distinction is so great that she thinks of them as two separate people. Chibiusa can be clumsy (not as much as Usagi was) and with Usagi around reminding her of both her mother and of herself, she naturally fights with her. They are living in the same house under the same roof. But when it comes down to it she would sacrifice herself for Usagi as much as Usagi would for her. Not because she won't be born, but because she truly loves Usagi. She doesn't really think of Usagi as her mother at all (as stated when she said "there must be some kind of mistake")

But if you study the anime you can find that Chibiusa and Usagi really like each other. Usagi jumps after Chibiusa to save her and begs her to let them grow up together and find both of their dreams at the end of SMSS. Chibiusa says crying, "Stupid Usagi, if I go to the future, I won't be able to stay with you, Mamo-chan and the others." Usagi spent all night making a rabbit out of the material of her favorite dress as a child while Chibiusa slept. (Sacrificing her sleep is a big deal!) Chibiusa couldn't say anything to express her gratitude. (Episode 127). Each time Chibiusa leaves they both cry. It effects them BOTH very deeply.

In the end, There was very little actual character development, as much more character insight. (in another words the character was static, you just learned more about them as the story went on.)

The anime did take the time to make sure she wasn't perceived as a brat for all time, but really didn't follow what happened to Chibiusa in the manga and her changes.

NA Dub
If the anime makes Chibiusa a brat, then Rini is ten times worse. The whiny voice that Rini debuted with marks heavily on her character. Scenes and lines were also "artistically" changed to make sure that she was even more of a brat. (Done by DiC) Overall most people judged Chibiusa on Rini.

The CWI dub did clean up Rini's reputation a little bit, with a better voice and less changed scenes.. they even cut a scene where originally Chibiusa faced Michiru. (which could have landed her back into bratdom by the fans, though I thought it was cute in the original!)

Overall her characterization is much more flat than the manga or the original anime.

Sera Myu
Depended on who played her. Check the Musicals section for more information.

Why She is So Cool!:
Most people coin her on the head as cute (some even say rabid). Some say she's just a brat. This is yet another set of stereotypes for Chibiusa. I don't really believe that's all there is to her. (after all look at the size of the personality profile ^.~). People who truly like her and understand her, like her because of WHO she is rather than WHAT she is. She is a girl who wants to become a lady. I think that's a rather admirable dream. Because of this dream she has a large desire to help and later on in the story. When her power does awakens she does all she can to help the Senshi team out. She always wants to help no matter how weak or strong she might be. She will even help at the expense of her life. She knows that most of her attacks (at least in the beginning) do little to no good, but she does her best and tries anyway. Some may call this cute, and some may find it pathetic, but actually helping when you know you don't have very much power shows not only guts, but a lot of heart. I like seeing her heart. Also when was trying and not giving up a bad trait in any character? (though some argue she is in the way and should let the more powerful characters handle it) You can see her as a very loyal friend (remember what she did for Momoko/Melissa in Japanese Episode 81, Dub episode 71?) It's easier to see what she really is like at the end of R, in the manga, and during SMSS. Overall I like her because despite her basis being a combination between Usagi and Mamoru, she has her own unique qualities. (This is quite a thumbs up to Takeuchi-sensei's genius!) She also has the traits that we love in Usagi, and some of the traits that make her her own character. She is well shaped and well rounded.