It was at this time that Catelyn Tully received a letter from her sister, Lysa, who communicated that she suspected her husband, Jon Arryn, had been murdered by the Lannisters. Stannis shared his suspicions with King Robert’s hand, Jon Arryn, who was murdered by poison soon thereafter.
It was Robert’s brother, Stannis Baratheon, who first became suspicious of the legitimacy of his brother’s heirs, whom he correctly suspected were actually born of incest between Cercei and Jaime Lannister. The entire war is centered around the illegitimacy of King Robert’s heirs, namely Joffrey, and his right to the throne upon King Robert’s death.
