Personality ☆ up to episode 10
Kaname Madoka seems to be a completely normal girl. She is cheerful and simple, with a casual interest in love letters and looking cute that doesn't go too over board. Her personality can seem just as simple and plain and Madoka can come off as a weak willed average girl, but the multiple timelines in her story show that Madoka is a stronger person than she thinks she is; she just needs to realize it.
In all timelines, Madoka is a happy person. She is surrounded by a loving family and happy friends. She may be a bit quiet, but she always does her best to be friendly and caring. In the first timeline, Madoka does not hesitate to befriend the shy transfer student Homura right away. Mami and her quickly become friends, to the point that Madoka is promising to not leave Mami alone. Madoka never once labels Kyoko as an enemy, and is quick to befriend her when the chance arises. Even in the case of Homura in the most recent timeline, Madoka tries to be friendly towards her. Madoka even continues talking to Kyuubey, even once shit has seriously hit the fan because of him.
This may be largely because Madoka is kind and naive. Homura makes a point to state to Madoka that she is naive, and that her kindness is a danger to herself. Because of this naivety, Madoka did not truly recognize any of the dangers of Puella Magi until she was slapped in the face with them. She was told it was dangerous, but did not take it seriously until Mami died, for example. During the instance of Mami's death, we also see some of Madoka's denial; Sayaka sobs tears of acceptance while Madoka just stares in disbelief, and doesn't truly come to terms with Mami's death until the next morning. Madoka wants to believe in the good in everyone and everything and will rarely reach a pessimistic conclusion without some hard evidence.
In a world where Mami does not die, Madoka contracts and pursues a happy magical girl journey where Puella Magi fight for justice, never noticing any signs that things may not be as happy-go-lucky as they seem... until everything comes crashing down. When things get bad, Madoka is able to finally recognize that she was a child and come to terms with the harsh reality. This is because, while she is a naive person who does not actively seek to find things wrong with life, she is not so stupid that she cannot learn from experience.
Madoka also has a strong, naive belief in everyone getting along and working together. This belief inspires her to want to make a Puella Magi duo with Mami, to ask Homura to look after Sayaka, and to never hate Kyoko, even after she engages in a life or death battle with Sayaka. She does not take sides in a conflict either; even when Sayaka was being attacked by Kyoko, Madoka could not bring herself to side with her best friend or Kyoko. In one timeline, when Homura reveals the truth of Soul Gems, Madoka never directly aligns herself with Sayaka's belief that it is a lie, even though her actions suggest she doesn't believe Homura. Again and again, Madoka is very sensitive to all sides of a situation, and supports peace and dissolving conflict without violence. Even when Madoka does form an opinion of her own, she is not always confident in it. She tries to get Sayaka to consider befriending Kyoko, but when Sayaka shoots that down Madoka just shuts up and starts rethinking things all over again. Madoka constantly looks for compromise and does not want to have a conflict with anyone, and is weak-willed enough to sometimes bend her opinion to avoid trouble.
This is because Madoka is an observant person, who typically ends up watching rather than acting. That much should be plain and obvious, as observing is her entire role in the show. Though she may seen like a clueless ditz based on all of the clueless faces she makes, Madoka is the type of girl to think things through. She is slow and uncertain with her decision making, and as a result, rarely commits to a decision. This has already been hinted at, because Madoka does not pick sides in a conflict, but just thinks both sides through and never says who she supports. She tends to sit on the fence throughout the whole show, her biggest decisions being to run away. When Mami dies, Madoka runs from the Puella Magi world she's just seen, even though she seemed almost ready to make a choice.
Madoka doesn't observe and decide alone either. When she's trying to decide something, Madoka will not hesitate to talk to people about it. She is generally in control of her thoughts and emotions, or at least trying to be. When Mami dies, Madoka avoids a major emotional break down until she is about to talk it through with Sayaka. Until she has a chance to deal with them properly, she makes an effort to put a lid on her feelings and act normally. When Sayaka contracts with Kyuubey, Madoka takes some time to think it through before she decides to accompany Sayaka on a Witch-Hunt, when she could have immediately asked. She also has many instances of discussing things with her parents and of chilling on the rooftop and talking deep talks with Homura and Sayaka.
When it comes to decision making, it can essentially be said that Madoka is not confident enough to come to her own conclusions. She needs people to talk to her and help steer her towards what she really wants. However, Madoka can act impulsively if she feels backed into a corner.
The decisions Madoka makes without talking to people are driven by strong emotions, generally fear. She stops the group suicide impulsively because she doesn't want to die, she throws away Sayaka's Soul Gem on impulse to stop Sayaka from fighting, and she shoots Mami because she's scared of seeing someone else die. It's only after Madoka commits these acts that she realizes what she's done and she usually crumbles under the pressure and confusion following her decisions, while seeming confident until they are completed. This is seen in her scrambling to run after stopping the suicide, her confusion and self-doubt after throwing Sayaka's Soul Gem, and her mental breakdown after it sinks in that she murdered Mami. It might also be noted that her impulsive decisions were all made in an effort to protect someone; Madoka will think for eons about herself, but will act quickly to prevent someone else from getting hurt.
Madoka's confusion and breakdowns are caused by the simple fact that she is running low on self confidence. Because she doesn't excel particularly well at anything, Madoka often feels useless. Though she tries to cope with her feeling of being burden in small ways, such as supporting friends and becoming the class nurse, she cannot easily shake her lack of self-worth. This causes Madoka to become confused easily, makes it harder for her to settle on decisions, and to cry a lot... Generally in private, because Madoka does not want to burden people with concern for her (she shakes off her family's concern when she cries at the table and doesn't have a real emotional cry over Mami until she's all alone).
Her lack of self-worth is only made worse by the fact that Madoka really truly wants to help people. Before the death of Mami, Madoka has almost settled on the idea that her wish is to help people and protect those she loves. In all of the timelines Homura experiences, Madoka has died because she wanted to protect people as a Puella Magi. In one timeline, she even asks Homura to destroy her Soul Gem, essentially destroying Madoka's soul, rather than allow her to become a witch and hurt people. Even when Madoka is laying there dying, she is thinking about the fact that she wants to protect people. When Madoka makes her miraculous wish, it makes it impossible for her to exist and sets her in line to absorb suffering for the rest of eternity, but Madoka is completely content as long as she is helping people. Kindness and loving everyone is a huge part of her character.
Human Madoka has little to no confidence. But Puella Magi Madoka does. When she's a Puella Magi, Madoka feels that she is worth something. And when Madoka feels like she's worth the life she's been given, she confidently works to protect it. There is a dramatic difference between the Madoka who prevents the suicide, scared out of her wits and lacking confidence in her ability to save those people, and the Madoka Magica who protects Homura in the first timeline. There's a huge difference in the Madoka who falls to her knees and breaks down when Mami dies in the line of duty, and is consumed by the terror of the witch Charlotte, and the Madoka Magica who looks down at Mami's corpse and Homura before she confidently heads off to fight the killer witch, all in the name of saving those precious to her. Even something as simple as her day-to-day interactions with people can be changed by a boost in confidence; when she is a Puella Magi, Madoka approaches Homura and leads the way to the nurse's office, while talking confidently and cheerfully with her. In another timeline, when she is not a Puella Magi, Madoka follows Homura and performs the same conversation, except this time she is stuttering and unsure. Her shy and timid nature will give way to a more happy ad upbeat girl when she feels good about herself.
In the end, unless Madoka feels confident in herself, she cannot and usually will not act useful, because she's too caught up in the fact that she doesn't think that she can be useful.
Lastly, and possibly most importantly, Madoka is a very pure girl and she is full of hope. It starts in her character design, where Madoka is noted for wearing pure and innocent white stockings, and ends in her purpose in the show. In Puella Magi, the transition from hope to despair gives off energy. And Madoka has the potential to be the strongest Puella Magi with the most hope, and therefore she can become the strongest Witch. This can be seen as the fact that Madoka is able to soak up a lot of despair before her heart breaks from the sadness. Even after all of the terrible things that happen in the show, Madoka still has hope that something good can happen. She believes that she can save Mami from her loneliness, that Homura can work with Sayaka and it'll turn out okay, and even once Sayaka is good and dead, Madoka believes with Kyoko that they can save her soul. Even after Kyoko, Sayaka, and Mami are all dead and Madoka Magica is crying her eyes out, she pulls herself together to fight Walpurgis Night with Homura.
Madoka might cry and break down a lot, but despite all of the tears she sheds, she is a strong girl who does not give up and wants to keep protecting people. She continues to look towards the future throughout the entire series. And when she finally makes her wish, it is to protect the Puella Magi who make a huge sacrifice for their own hope and wishes. Madoka essentially becomes Hope when she makes her wish, which is quite the indication of just how much Hope is in this girl's character.