Tommen was said to be the son of Robert Baratheon and Cersei Lannister but that wasn't exactly the case. Like his two siblings, his true father was his uncle, Jaime Lannister. Prince Tommen was essentially a minor character in the first two seasons: he visited Winterfell with his family, was shown visibly upset when Myrcella was sent to Dorne, and was nearly poisoned by Cersei during the Battle of Blackwater. Tommen was weak-willed and often ridiculed by Joffrey, but that changed in season 4 when he took over as Lord of the Seven Kingdoms.
In the television adaptation Game of Thrones , he is played by Callum Wharry in seasons 1 and 2 and by Dean-Charles Chapman in seasons 4 , 5 and 6. Tommen is plump, with long white-blond hair. Tommen, unlike Joffrey , is regarded as a good-hearted lad who always tries his best. Many other characters except his mother  believe that he would be a much better king than Joffrey. Tommen once adopted a fawn as a pet, but his elder brother, Prince Joffrey , later killed and skinned the animal. At Winterfell, Tommen spars with Bran Stark using wooden swords.
Brynden Tully (“The Blackfish”)
He has an older brother, Joffrey , and an older sister Myrcella with the same obfuscated parentage. Tommen is good-natured and passive in contrast to his brother Joffrey, who sometimes bullied Tommen for amusement. Tommen accompanies his family north to Winterfell via litter with their mother. Upon arrival, he and Myrcella are visibly awed by the mighty castle.
Martin's "A Song of Ice and Fire" book series were not expecting. First and foremost, there was the fact that Sansa Stark is now betrothed to Ramsay Snow Bolton, which is a sharp turn from her storyline in the "Feast for Crows" book. But even more visually shocking for readers and viewers alike was the love scene between King Tommen Baratheon and Margaery Tyrell -- which, again, never happens in the books, due to the large age difference between the two characters.