Evil powers have seduced Nikabrik, playing on his sense of grievance over the way the Telmarines oppressed and abused all Narnians, and also over the way Aslan and the Narnians mistreated (and still, in his opinion, take advantage of) the Dwarves. They hint to him that he can have enduring power, even though history clearly shows that no one’s power lasts forever, not even Aslan’s. After a time, evil finds a way back into the world and must be defeated once again. He wants power for himself and his people, and if Caspian won’t protect the Dwarves’ interests adequately (in Nikabrik’s opinion) then he will take matters into his own hands. Essentially, Nikabrik challenges Caspian’s right to rule in this moment and seems about to stage a coup.