Who would've guessed it?! Jaime Lannister (Nikolaj Coster-Waldau) is an official Good Guy. At the end of the Game of Thrones season 8 premiere, a newly dark-haired Jaime gets off of a horse in Winterfell and locks eyes with Bran (Isaac Hempstead Wright), signaling that their character arcs have officially come full circle.
Eight seasons ago, a much blonder, much smarmier Jaime pushed Bran out of Winterfell's highest tower after the tree-climbing Stark son accidentally caught Jaime and his sister, Cersei (Lena Headey) in a moment of intimacy. The moment sent Bran, Jaime, and frankly all of the Stark family members on their respective paths. Years later, Bran and Jaime have come together again — only now, they're on the same side. Jaime has officially ditched Cersei — and he's come to warn the others at the Great Game of Thrones Reunion in the North.
Last season, Cersei — duplicitous she-snake that she is – promised her forces to Jon and Daenerys. As she later revealed to Jaime, though, it was all a ruse. "Let the Stark boy and his new queen defend the North. We stay here, where we've always been," Cersei said, not quite understanding the magnitude of the White Walker army yet (unlike us, she hasn't seen the aerial shots). Cersei's planning to use the Golden Company to fund her war against Jon and Daenerys.
But Jaime can't go along with Cersei's plan in good conscience. Jaime had vowed to go North and join the gathering forces at Winterfell. His years on the road taught him what concepts like "promises" and "decency," typically foreign to Lannisters, really mean. So, despite Cersei lording their baby over him, Jaime leaves King's Landing.
Technically, this is treason — Jaime acted in defiance of his queen. If Jaime were anyone else, Cersei would've sent the Mountain after him. As it turns out, Cersei does still have a shred of a heart, however "weak" that makes her. All of her affection is directed toward Jaime and their unborn baby, a final chance at rebuilding their family now that their three children are dead.
Though that affection doesn't last long. In the season 8 premiere, Cersei hires Bronn (Jerome Flynn) to murder her brothers, Jaime and Tyrion (Peter Dinklage), using the same cross-bow that Tyrion used to kill their father. "This family," Bronn sighs. He is right.
Jaime's world-view and moral compass has expanded beyond Cersei's. He understands the big picture. He's traveling North to save the world, not just the Lannister family line.
While it won't compare to breaking up with your sister-lover, traveling to Winterfell will bring its own set of socially awkward circumstances for Jaime. For one, Jaime is responsible for Bran Stark's paraplegia (though now that Bran's the Three-Eyed Raven, he'd probably assuage Jaime's guilt by unemotionally saying, "It was written"). Arya Stark (Maisie Williams) will certainly be less friendly. Though Jaime is not on her kill list, he's a Lannister, and therefore not to be trusted.
Finally, Tyrion Lannister (Peter Dinklage), the odd one out of the Lannister sibling trio, knows about Cersei's pregnancy. Who knows how he'll use this gossip? Maybe he'll call the TMZ tip line; maybe he'll relish in the simple fact of having something on his cool older brother.
Still, Jaime bears information so crucial it'll melt any icy glares. Jaime has proof of Cersei's double crossing and details of her plan to use the Golden Company to fund an army. With these findings, Jon Snow (Kit Harington) and Daenerys Targaryen (Emilia Clarke) can process the fact that they're slowly being sandwiched by enemies in the North and South — and strategize.
In the end, Sansa (Sophie Turner) was right. Jon never should've trusted Cersei in the first place.