Question: are eragon and murtagh brothers?
Answer: Murtagh Morzansson – the human son of Morzan and Selena, Eragon's half-brother. Eragon first meets him in Eragon and travels with him to the Varden, where he is mistrusted for being Morzan's son. In Eldest, Murtagh is kidnapped by the Twins and forced to serve Galbatorix after the dragon Thorn hatches for him.