Skyland

I’m pretty sure it’s about Kaladin. Darkened twin just refers to his grief riddled persona. Often a time during deep bouts of depression, it’s as if you are another person, a person who has completely different outlook on just about everything. That person looks exactly you though. Almost as if he/she is a twin who sees the world through a darker shade. the entire quote is the embodiment of what Kaladin did. When, despite Ishar throwing the weight of not only the 9 broken heralds madnesses but also odium’s tainted power onto him, he stood up. He stood up with his darkness on his back keeping him down, because as he said, sometimes just getting up and moving made him feel a bit better (the light he seeks).