Trivia: Of the 43 actors credited as being part of the main cast, Peter Dinklage is the only American.
Trivia: Although he plays the eldest Baratheon brother Robert, in real life, Mark Addy is nearly 8 years younger than Stephen Dillane, who plays the middle brother, Stannis. Additionally, the real-life age gap between Dillane and Gethin Anthony, who plays the youngest brother, Renly, is more than 26 years.
Answer: Basically it's because he broke his vow. A member of the Kingsguard is sworn to protect the king at all costs. Jaime elaborates more on the deed to both Catelyn Stark and Brienne of Tarth, telling Catelyn that no matter what course of action he took, he would be breaking one vow or another (i.e. if he obeyed the king, he would conversely be disobeying his own father), and telling Brienne that the Mad King was planning on burning all of King's Landing, but he did not bother to tell Ned Stark that. Ned Stark felt that killing Aerys was dishonorable and excessive. Robert Baratheon still could have usurped the throne without Aerys being killed.
Phaneron ★