Outside Storms End, 299AC
The two brothers agreed to meet alone. This meant that they were out of earshot but inside arrow-shot of their retainers. And it were expressly their Stormlander backers which had forced the two to talk again, the Stormlanders not being keen on a Civil War. The Baratheon's agreed to a pow-wow for the sake of appeasement of their bannermen.
Hence at this moment Stannis and Renly were glaring at one another and grinding their teeth or smirking, depending on the brother's in question temperament. They were at a stalemate – one upheld his claim by seniority and "right", the other by popularity and "might". Not an exactly surprising state of affairs. A cynic might had said that their meeting was a waste =of time for everybody concerned and that they should man up and resolve their differences the manly, mature way - with live steel.
"You want to be king, I want to be king, how can we reconcile that?" – the younger Stag asked. – "Or maybe we take turns?" - he laughed at his own jape. - "You are king on even numbered days and I rule on odd numbered? And we rule jointly on High Feast days?" – he continued in a similarly light hearted vein.
The elder sibling looked upon him as if he had grown another head - just like Maelys Blackfyre was said to have.
His brother – who had inspired the "dumb brunet" joke genre – actually had an idea?
"You say we alternate..." – Stannis began. - "Maybe not on a day by day basis, but ..."
After much teeth grinding and boyish giggles an alliance was forged.
The GrimStag and the PoofStag crushed all before them. First the Lannister army under Lord Tywin – which rushed east from the Riverlands to block their passage - tried to deny them the fords across the Blackwater River. This force was outflanked by an amphibious landing to the east of Kingslanding, forcing Lord Tywin to retreat inside the walls or be cut off from the city. Incapable of withstanding any sort of siege due to lack of food Lord Tywin tried to buy safe passage of his family to Casterly Rock by threatening to kill all hostages. King Stannis replied – "no."
After Tywin had killed most of the hostages in sight of the besieging army the Baratheon Brothers order an assault and took Kingslanding by storm. While most men of the Lannister family died in the fighting, like lord Half-Man Tyrion or King Joffrey the Illborn, Tywin himself – albeit wounded - was captured. Queen Dowager Cersei – once Baratheon banners were seen approaching the Red Keep – killed herself, expecting no mercy from her good brothers and preferring death to dishonour.
As retribution for the crimes of the Lannisters the Baratheon Kings had all surviving members of the House executed in front of Lord Tywin. Tommen Waters, brought in from Rosby, met this fate as well. Top ranked functionaries of the Usurper – Lord Baelish, Master of Whispers – were executed as well – when the Stag Kings had compared notes on who-told-them-what-and-when this had damned both men beyond any reprieve.
The Baratheon host then marched westwards. The King in the North and the Trident Robb Young-Wolf Stark, who refused to bend the knee to the Iron Throne and ridiculously demanded compensation for the death of his sister - one of the hostages massacred by Tywin - at the hands of the Lannisters, was smote down and killed like a mad dog. Other casualties included the last two male Tully's – both Brynden "Blackfish" and Edmure "Floppyfish" falling in battle.
Stags United then invested Casterly Rock and subdued the whole of the Westerlands. House Lannister was attained, all men being killed while the women either forced to join the Faith or to marry second or third sons of lords or knights loyal to the Baratheons.
The Realm was then reorganised on a scale last seen at the Age of Targaryen Conquest. The North brought to heel, with Bran the Broken as its lord. As he could not sire children Rickon was to be his Heir. Once the boy contracted rabies, however, Jon Snow was extricated out of the Nights Watch and made the next Lord of Winterfell.
The Riverlands were divided, with the easternmost part – around Lake Gods Eye - being added to the Crownlands. The western part was given to House Frey, the first Riverlander House to abandon the Lady Catelyn, the Last Pretender from Houses Stark and Tully.
The Westerlands were given to House Florent. The price for becoming Lords of the Rock was the relinquishing of all their holdings in the Reach. Neither the Florents nor the Tyrell's were fully happy with this solution yet both sides found it acceptable – thus marking it as a textbook example of good diplomacy. The former Florent lands were granted to Garlan Tyrell who established a cadet branch of House Tyrell – House Foxyrose.
Once the might of the Seven Kingdoms was brought to bear the Others were easily repulsed and thus peace reigned over Westeros.
When she came of age Lady Shireen became Lady Paramount of the Stormlands. To keep the Stormlands in the family – and due to King Renly having a weakness for the boy – Edric Storm was selected to be her consort. The Florents had mixed feelings about this. With the Realm and his daughter's fate secure, King Stannis honoured the Storms End Agreement and stood down from the joint kingship, taking the Black. He ultimately became the 1003rd Lord Commander, the first Baratheon and 22nd Stormlander to reach that rank.
In an ironic twist of fate King Renly and Queen Margery had only daughters – seven in number. Hence when in 315AC King Renly died of the "pillow-biters pox" contracted from Ser Loras, he was succeeded by Queen Shireen and Prince-Consort Edric.
The brothers agreed to rule together until Shireen came of age and received the Stormlands. Then Stannis was to abdicate. The line of succession was agnatic - all males before any female. It ran like this: Stannis, his sons, Renly, his sons, Stannis' daughters, then Renly's daughters. Hence, with Renly having daughters only, the throne reverted to Shireen.