Renly Baratheon
The youngest Baratheon brother, Lord of Storm's End: charming, handsome, and beloved at court, with the easy warmth neither of his brothers could manage.
The fuller tale
Renly got Robert's face, Robert's charm, and none of Robert's scars — he was a baby during the rebellion that made his brothers, and grew up its beneficiary rather than its veteran. Lord of Storm's End at a boy's age (his brother's slight to Stannis, though Renly never treated a castle as an apology), he came to court young, sat on the small council as master of laws, and made himself the most popular man in King's Landing without apparent effort. He collects friends the way Stannis collects grievances, and the difference between the brothers is the story's tidiest study in how charm and right are separate inheritances.
The center of his life is Highgarden. His bond with Loras Tyrell — squire, champion, and the love the show states plainly while the books leave it in perfumed subtext that fools nobody — welds House Baratheon's youngest branch to the realm's richest army. When Robert dies and the succession shatters, Renly's logic is breathtaking in its honesty: setting aside the incest question entirely, he is simply better at this than Stannis, and the biggest army makes the finest king. Why should the order of birth outrank the judgment of a hundred thousand swords? He crowns himself in the Reach, weds Margaery Tyrell, and turns the march to war into a royal progress with tournaments.
The tale keeps testing his crown's weight and finding it light. His parley with Stannis before Storm's End — the books give it a peach, offered and refused, that Stannis broods over for the rest of his story — is Renly at his best and worst: funnier than his brother, righter about people, and completely unserious about the arithmetic of claims and gods. Catelyn Stark, visiting his silk-and-summer camp, delivers the verdict the story endorses: they are the knights of summer, and winter is coming. Renly's answer — that summer is precisely what he's offering — is the most likable wrong position anyone takes in the whole war.
What Renly means to the larger tale outlasts his part in it. His crowning breaks the realm's assumption that succession is a fact rather than an argument, and every later claimant walks through the door he opened. His hundred thousand swords, inherited by others, decide the Blackwater. And in Brienne of Tarth — the mocked, earnest woman he treated with simple courtesy at a ball once, and who repaid it with the fiercest loyalty in the story — he leaves behind the strongest evidence for his own theory of kingship: that being kind is a form of statecraft, and that people fight hardest for the lord who saw them.
The page and the screen
The show makes explicit what the books imply: Renly and Loras as lovers, Margaery as a knowing partner in the arrangement, and Renly's discomfort with violence — the show's Renly is queasy at blood, where the books' version rides to melees happily enough and simply prefers politics to practice yards. The books give his kingship more texture: the Rainbow Guard (a Kingsguard of seven colors, with Brienne winning the blue at Bitterbridge), the peach at the parley, and a sharper strategic mind — his plan of starving King's Landing while his brothers' factions bled each other was working. The show trims his war to a few tents; the books make clear how close the realm came to King Renly, First of His Name.
In the books
A Clash of Kings. In Wolves and Krakens — A king of summer with the finest army and the least urgency.
Where they stand, season by season
Their fate — if death has found them, it is written here. Open at your peril.
The show: Killed by a shadow (S2·E5)
The books: A shadow with his brother's face (ACOK, ch. 34)
He crowned himself with a hundred thousand swords at his back, and none of them could guard him from what Melisandre birthed in the cave beneath Storm's End. A shadow with Stannis's face put a blade through his heart in his own tent.
Both tellings kill him the same impossible way, in front of the same two witnesses. On the eve of battle against Stannis — dawn in the books, with Renly armored and joking about his brother's punctuality; night in the show's tent — a shadow crawled into the light of the candles wearing something like Stannis's face, and put a blade through the king from behind his own guarded perimeter. It was Melisandre's working, birthed beneath Storm's End and fed on king's blood, and it made Catelyn Stark and Brienne of Tarth the only living witnesses to a murder no court in Westeros had language for. Brienne was blamed, and has spent the story since outrunning and outliving the accusation. His army went to other masters within days — the Tyrell strength to the Lannisters by marriage, the storm lords to the brother whose shadow killed him — which is as concise a summary of the War of the Five Kings as the tale offers.