In Game Of Thrones Jaime's character is shown to be bad and ruthless in the beginning. He pushes a little kid off a window. Later he's shown to have honor and sympathy and looks after Sansa, tries to get her to safety. What causes his change? He's also been through his own set of difficulties. What causes him to take seriously to keeping his word to Catelyn Stark? After all he didn't care much when he tried to kill her younger son.
There are a number of things that change him, but the defining moments are:
- Meeting Brienne
- Losing his hand
- Opening up to someone (Brienne) about why he killed the Mad King
These completely and totally change his character and make him determined to redeem his honour (which he himself defines) in any way that he can.
There are a few things contributing to Jaime's colossal character change.
Being away - Season 1 and start of Season 2
He is captured by Robb's army and remains a very well guarded (barring one half-escape) for over a year. During this time he's away from his sister, son and the rest of his family. Simply being away distances him from the toxic atmosphere of the Lannisters. Now, this is by far the least significant of the events that lead to his character change, but I do think its worth noting.
Lady Catelyn, starting to know Brienne and honour - Season 2
When he was set free, a few things happened. Firstly, he was trusted by Lady Catelyn to return to King's Landing and free her daughters. Whilst initially it seems likely he has no intention of keeping his word, the actions of Brienne will later lead to him becoming far more concerned with keeping this promise.
Secondly, Brienne was tasked to be delivered and stuck absolutely steadfast to her task. In Valar Morghulis, the Season 2 finale, she even killed Stark men, all in the name of doing the task she was set - to deliver her prisoner in her service to Lady Catelyn.
This has a definite effect on Jaime - here is a woman who follows her code of honour. She is not on one side or another. Jaime appears to start thinking like this himself come Season 4 (and Season 5 and beyond).
Brienne's peril and the Loss of his hand - Season 3 beginning
His life is built upon his strength as a knight. Despite the subtle changes already over him in Season 2, he still tries to fight Brienne in Season 3 and break free (although whether he would have killed her if he had bested her is definitely debatable).
However, due to starvation and exhaustion (as the book is clear to point out), he is defeated. Fascinatingly, later that day, he shows one of his first genuine acts of kindness in the series - he tells Brienne she will be raped that night, and that she should not resist, or they will kill her as she is nothing to them.
Whilst this may seem cold or hurtful, it's also truthful. He realised what could befall her and didn't want it to happen. He even goes as far as to lie about how her homeland, The Sapphire Isle, got its name (saying it's because of all the sapphires). This leaves the men to leave her alone in the hope of getting a ransom.
Already, it's clear that something about Brienne has gripped him. Perhaps she reminds him of a young Jaime? Despite this, he has certainly not changed yet. Instead, at this point, he simply appears to have some sort of grudging respect for her.
Everything changes when he loses his hand. This was his greatest asset. He was a colossal fighter, the youngest ever Kingsguard member - and losing his hand stripped him of everything he had spent his life fighting for in a single swoop. He begins moping, and is furiously berated by Brienne for acting like a woman. Despite her fierce criticism, he actually follows her advice. She helps him beginning eating and drinking again. Once more, her strength and commitment to honour appears to sway him.
The Truth about the Mad King and Jaime - Season 3 - defining moment of change
The bath scene at Harrenhal, in Kissed by Fire is his defining moment of change. After slipping into a bath with Brienne, and initially insulting her, he completely opens up and tells her (and the audience, for the first time), the true story of the Mad King...
One of Jaime's biggest frustrations is the lack of respect he is given. He served under the Mad King, in the Kingsguard - the youngest ever member of the order. However, he learned (and we learn in A Storm of Swords) that he was chosen as a slight against Lord Tywin, so he wouldn't be the heir to Casterly Rock. Despite this, he remained in the Kingsguard.
We learn from the books in particular how difficult it was for him during this time. For example, when Brandon and Lord Rickard Stark (father of Ned) were murdered, he had to be reminded by Ser Gerold Hightower that he swore an oath to guard the king, not to judge him.
Finally, when Rhaegar and Robert go to war, and it becomes clear The Targarayens will lose, The Mad King orders the city be set ablaze. He also orders Jaime to bring him his father Lord Tywin's head. This is the last straw for Jaime, who turns his back on his King and slaughters him. He could not stand by and watch the entire city be destroyed, and so many people to perish.
His reward? The title Kingslayer and an almost universal disdain for turning his back on the person he swore to protect. He broke his honour, and should have died protecting him, according to his oaths. This disdain and lack of respect led to resentment which continued to bubble inside him, making him crueller and more callous.
I think this is the true final moment of change for Jaime. It's not that he becomes a good person. It's not that all his sins are forgiven. It's just that something inside changes and from that point on becomes linked to Brienne and determined to keep a sense of honour.
When he collapses at the end of his story, she cries out for help for the Kingslayer - and he corrects her. His name is Jaime.
Rescuing Brienne - Season 3 ending
After leaving Harrenhal for the capital, Jaime realises what is going to happen to Brienne, who has been left behind. He demands his group returns and rescues her from a bear, in a hideous gladatorial battle she's been forced into. Together, they depart for King's Landing.
For the first time, he has been able to save her.
And he's actually done something honourable, which she appreciates - it's the first genuine appreciation he has had in a long time, and continues to change how he views both Brienne and the world.
New sense of honour and distancing from Lannisters - Season 4 beginning
This continues in Season 4, when he returns to the capital, but refuses his father's orders to leave King's Landing. He chooses to stay in the Kingsguard, to protect the King. Of course, with his stump hand he's of little use - it's his name and the legend of his fighting which affords him his respect. But, inspired by Brienne, he is determined to stay and redeem any honour he can.
In one of the more memorable scenes in Season 4, he has sex/rapes Cersei, next to Joffrey's body. This is unquestionably one of the most tortured and complex scenes of the series. At that moment, he both loves her and hates her. It's a connection to the long past he has, and yet a reminder of how far away from her he now is. He even tells her:
"You're a hateful woman, why have the gods condemned me to love a hateful woman?!?"
This moment forever changes their relationship.
When next they meet, he is trying to convince her of Tyrion's innocence and is kicked out of her room. The dynamic between them (as of yet) has never recovered.
The action is brutal and horrendous. It shows his change, but also shows how cruel and cold he can still be. It's another reminder that the world of Game of Thrones is not simply good versus bad.
Brienne's departure and a commitment to the future - Season 4 mid to end
At the start of Season 4, Jaime refuses to release Sansa to Brienne - but only because by this stage Lady Catelyn and Robb are dead and he genuinely believes she will be safer in the capital.
When Joffrey dies though, Tyrion is arrest and Sansa is missing, he knows she is a prime suspect and is in grave danger.
Jaime sends Brienne, with new weapons and armour, on a mission to find Sansa and protect her - especially from his sister. This poignant scene reminds us of both how much he now respects and trusts her Brienne, and contrasts starkly with how much he distrusts his own sister, whom he pined over for so long whilst being captive.
His final act of honour in Season 4 is to rescue Tyrion from a fate he knows he doesn't deserve, setting in action a complex range of events that you'll see in Season 5 (and that will be continued beyond).
He is a wonderfully complex and bizarre character, with varying and often confusing attitudes towards both violence and other people. To quote from the GoT Wiki:
Jaime's attitude towards violence is also complex: he threw Bran Stark out a tower window to kill him, but later saved Brienne from being raped (and then fed to a bear) by Locke's soldiers. The difference seems to be that after witnessing the deprivations [sic] of the Mad King, needless violence and brutality deeply offend Jaime, though if he decides that violence and murder are absolutely necessary he will ruthlessly carry it out himself. He threw Bran out of a window because had the boy reported that he saw the incest between Jaime and his sister, Cersie, the woman he loved, and all of their children would be executed, so he felt he had no choice.
There is nothing simplistic about his character, but the one clear thing is his hatred of the lack of respect he is given for killing the Mad King. If Ned or Robert had done it, they would be heroes. Because he did it, breaking his oath, he is treated with contempt.
When he meets Brienne though, loses his hand and finally confides in someone what he did and why, he changes. The look in Brienne's eyes during his speech tells a story too - suddenly his actions have a very different meeting.
This is the defining moment after which he completely changes. He is still ruthless, but rather than following his family's code of honour, he appears to follow his own - largely inspired by his adventure with Brienne.
I'll offer up a short answer alternative:
He didn't change. He was always this way. He just emphasized different persona traits at different times. He's always been loyal to family, and has also always possessed a sense of honor. What did change over time was how heavy a shadow is father cast upon him. Obviously, his time away from said father has allowed him to reveal his more nobler traits.
I would argue this is true for both Lannister brothers.
Plus, they're growing up. As nobility, they were somewhat coddled well into their early adulthood. They're not coddled anymore.
A Lannister always pays his debts. He can be cruel of course, but if he gives his word and owes someone, he keeps it. Pushing the kid was about protecting himself and his sister. Of course he could have done this another way, but he was more practical that way.
There are some changes in his character of course (I read all the books), but the prominent reason for looking after Sansa is because he has a sense of honor. He would be no good at all if he wouldn't even keep his word and pay his debt.