Game Of Thrones Series
King Joffrey I Baratheon was the eldest son and heir to King Robert Baratheon. Though believed by most to be the eldest son of Robert and Queen Cersei Lannister, Joffrey is actually a bastard born from Cersei's incestuous relationship with her twin brother, Ser Jaime Lannister of the Kingsguard. He is the older brother of Myrcella Baratheon and Tommen Baratheon, both of whom share the same parentage with Cersei and Jaime Lannister.
Joffrey is believed to be the oldest son and heir of King Robert Baratheon and Queen Cersei Lannister, both of whom entered into a political marriage alliance after Robert took the throne by force from the Mad King, Aerys II Targaryen. In reality, his father is Jaime Lannister, the queen's brother and the Lord Commander of the Kingsguard. His sole biological grandparents, Tywin and Joanna Lannister, were also first cousins.
Joffrey takes after his mother in terms of looks and personality, his blond hair being a subtle clue that he isn't really a Baratheon, who famously always possess black hair even when one of their parents possesses blond hair. Cersei herself lets it slip to Catelyn Stark that she once had a child with black hair who died prematurely before she had Joffrey. He is usually accompanied by his sworn shield, the formidable Sandor Clegane, better known as the Hound. Even before he ascends to the Iron Throne, Joffrey is spoiled, arrogant, cowardly, and sadistic; however these traits are further exacerbated upon Robert's death and his ascension to the crown.