Few in Westeros could accuse the "Kingslayer" of having a reputation for honesty and honor, but until the tail end of Game of Thrones' seventh season, Jaime Lannister was at least known to be loyal to his family. Now, he's even put that characteristic on the line by disobeying his sister-slash-lover to head north and help with the looming Night King invasion.

According to actor Nikolaj Coster-Waldau, Jaime's not doing so to "spite" Cersei (Lena Headey) but out of a sense of duty. Cue that "I promised to fight for the living" line from the trailer.

In an interview with TVLine, the actor explained, "Even though he's known as the most dishonorable man, he is a man of his word. The promise they made was very important, but it also was the right thing to do."

Game of Thrones Season 8: Everything We Know So Far

Moreover, Coster-Waldau said that Jaime feels a sense of obligation to follow through on his pledge to fight against the wights because of who received his promise.

"He gave his word to his brother, who is the only person he truly trusts," the actor said. (Though he did then glance at actress Gwendoline Christie and add, "Of course, together with Brienne.")

Going into Season 8, there's been a lot of talk about how Jaime's decision to leave King's Landing might affect his ailing relationship with Cersei, which has been the definitive connection of his entire life, quite literally speaking. However, Coster-Waldau's words do remind us that Jaime has also always been one of the few Lannisters who truly care about Tyrion (Peter Dinklage) and doesn't seem to judge his physical appearance or begrudge the fact that their mother died giving birth to him. And now, it looks like Jaime may have realized that it's his younger sibling who really deserves all of his fealty and trust at long last.

So, could this be a turning point for Jaime? By turning his back on Cersei, for whom he's committed so many atrocities in the past, could Jaime finally recover some semblance of a reputation at Tyrion's side? Will he finally shed the nickname that's haunted him for so long by aligning with his much more clever relative? We'll find out soon enough.

Game of Thrones Season 8 premieres Sunday, April 14 at 9/8c on HBO.

PHOTOS: Game of Thrones Season 8

<a href="https://www.tvguide.com/celebrities/lena-headey/161706/">Lena Headey</a> as Cersei Lannister, <a href="https://www.tvguide.com/tvshows/game-of-thrones/305628/"><em>Game of Thrones</em></a>Lena Headey as Cersei Lannister, Game of Thrones