I've divided the season into the individual arcs, based in the locations where the primary events take place. Hopefully it's easy enough to follow. I've even included my favorite fancastings for characters we never got.
Winterfell
After recieving a summons to Dragonstone from Olenna Tyrell and Ellaria Sand, Jon ignores Sansa's protests and insists on heading South to convince the newly arrived Targaryen Queen to let him mine dragonglass. This leaves her alone to try and corral the bickering lords and ladies of the North, avoid Littlefinger's scheming, and deal with the return of her missing brother, who arrives alive but tempermental, distant and babbling about mad legends from beyond the Wall.
Brienne of Tarth is now Master at Arms while Podrick Payne is Captain of the Guard. Among the leaders, Sansa finds her most trusted confidantes are Lyanna Mormont and Yohn Royce. But House Mormont holds little power and Bronze Yohn is an outsider, sworn to his lord, Petyr Baelish. To maintain control, Sansa must win the favor of Lord Wyman Manderly, now the most powerful man in the North, both in terms of wealth and military. In doing so, sparks of romance begin to fly with Wyman's cousin's son, Mycah (played by Alex Hogh Anderson). While a still traumatized Sansa is reluctant to even consider a relationship, they grow very close. Unbeknowst to either of them, this is all according to Wyman's plans.
Bran, meanwhile, suffers from a mind torn apart by his new powers and haunted by mysterious visions. He refuses to use his powers of his own accord, for doing so left him scarred by the Night King and got Bloodraven, Summer, Leaf and Hodor all killed. However, he shares just enough of his visions to make Sansa start to believe him and Littlefinger grow paranoid, thinking the boy is faking his paralysis.
When the Brotherhood Without Banners take shelter on their way to the Wall, Maester Wolkan is murdered. All evidence points to Wyman, who was offered the position of Warden of the North in exchange for Jon's head. Wyman, Mycah and all the Manderly men are banished back to White Harbor. However, desperate for aid as more smallfolk overcrowd the Winter's Town, Sansa sends Littlefinger to offer her hand to Mycah in exchange for Manderly loyalty.
Jon Snow's Travels
Jon is running all over the place this season, dragging poor Davos along for the ride. They reach Dragonstone and successfully gain permission to mine the dragonglass. However, tension is ever-present, given Ned Stark's role in overthrowing Daenerys' father and exiling Jorah. But the two young rulers cannot help but be drawn to each other.
Jon develops a strange bond with Rhaegal and tries to convince Dany to bring her armies North to fight the Night King. She does not fully believe in the legends, even after the miners discover ancient cave paintings from the Long Night. Jon vows to bend the knee if she comes to their aid, but she first leaves to wage war in the south. In parting, she promises she will return to him.
Jon and Davos leave with the glass and Obara Sand. Disenfranchised with the war for the Throne that destroyed her family, she seeks to find true glory in battle against a greater threat. They are unaware of the Manderly betrayal, however, and their ship is siezed at White Harbor. Jon and Obara escape and ride to the Wall, with a map Jon copied from the caves, leading to a hidden valley in the Land of Always Winter.
Davos, however, is taken prisoner. When Littlefinger arrives on mission from Sansa, the treacherous man reveals he is still reporting to Cersei, and demands Jon's Hand be executed as proof of their loyalty. On the gallows, Davos gives a final speech before his apparent death. Before he goes, Littlefinger arrogantly reveals to Wyman that he killed the maester to frame the Manderlys, ensuring Sansa is reliant on him.
Dragonstone
Daenerys arrives to find Olenna Tyrell and Ellaria Sand flying the Targaryen banners over the ramparts of her ancestral home. After some bickering between her new allies, particuarily due to their distaste for Tyrion, they begin to strategize. All but Tyrion advocate an immediate storming of King's Landing. But when Missandei, concerned for loss of life, sides with Tyrion, Dany chooses her Hand's path.
Once her allies set sail, Dany meets a new one - Jon Snow. Their initial distaste builds to affection, while Tyrion begins to train Missandei in reading and ravenry. She hopes to break down the Citadel's gender barrier to become her queen's Grand Maester. However, bad news soon arrives. While Grey Worm has taken Castlery Rock and secured the support of its castellen,Tywin's low-class but well-liked cousin Ser Damion Lannister (Jared Harris), Yara's fleet is destroyed by Euron Greyjoy, Highgarden conquered by the Tarlys, and Dorne overtaken by Princess Arianne Martell.
Furious at this turn of events, Dany bids farewell to Jon and leads her dragons and Dothraki to take back Highgarden, leaving Tyrion and Missandei behind. Tyrion sends Missandei to Oldtown to answer a petition from the Faith, which hopes to crown their own queen after Cersei destroyed the Sept of Baelor. With no dragons to defend it, the fortress falls to Euron Greyjoy, although Tyrion does manage to stab out the pirate's left eye in the process.
Dany and her army first ambush the Lannister's returning loot train, a massive victory. Afterwards, Dany executes the defiant Tarly's, much to Varys' horror, and marches on. Overconfident, their forces are entrapped in battle by the armies of the Lannisters and the Reach, armed with Scorpion Bolts and rope traps designed by Qyburn to trip up the Dothraki. Dany retreats to Castlery Rock, with three badly wounded dragons and a shell-shocked Dothraki horde.
The Iron Fleet
While disappointed by Daenerys' choice of strategy, Yara Greyjoy obeys her queen nontheless and sails with Ellaria Sand to Sunspear to collect the Dornish forces. This proves unsuccessful, as Arianne Martell has claimed her father's titles and only allows a handful of soldiers loyal to the Sand Snakes to sail back. Yara takes a liking to Dorne and the kingdom's accepting attitude towards her gender and sexuality, but Theon is miserable surrounded by painfully hot food and beautiful women he no longer feels he can speak to.
On the journey back, the fleet is ambushed and devastated by Euron Geryjoy, under the cover of a thick black fog, an unnatural concoction of squid ink and sorcery from the Shivering Sea. Nymeria is slain and Yara, Ellaria and Tyene taken prisoner. Only Obara, Theon and a handful of Ironborn escape. Euron delivers the Sand Snakes as a gift to Cersei, but keeps Yara on his ship "for company".
After their return, Theon is reunited with Jon, whom he hopes will either forgive him or kill him, ending his misery. Jon does neither and Theon instead attempts to free Yara with the remaining Ironborn. This too ends in failure, when Euron's shadowbinder kills all but the Greyjoy siblings with spectral assasins. They are dragged back to the city, where Euron and his priests and soldiers have made a blasphemous camp in the ruins of the Sept of Baelor.
The Riverlands
After finishing off the the men of House Frey, Arya heads back south on the King's Road, wearing Black Walder's face. Unawares, she has been followed back to Westeros by another Faceless Man (Doug Jones). Her lack of knowledge in the magic she is wielding has terrifying effects when she begins to dream Black Wlader's memories, including his murder of her mother. She is attacked by the Faceless Man. She survives by the timely intervention of Nymeria's wolfpack, but is near-lethally wounded.
Meanwhile, Lady Genna Lannister (Camryn Manheim) has freed Edmure Tully, who at last pledges fealty for his family's sake, and seeks the killer of her Frey husband and sons. Stopping at the same Inn, she sees through the Black Walder disguise and storms Arya's room while she is gone, finding her collection of faces. Genna leaves for the capital, but Arya mistakenly follows the caravan back to Riverrun, where she collapses from her wounds.
Edmure is at last reunited with his wife and baby boy, named Robb, only to be forced to decide what to do with Arya while she is nursed back to health. The Lords Jonos Bracken and Tytos Blackwood (Rupert Graves) are on opposite sides of the debate. To protect his family, Edmure reports his find to Cersei. Before the girl can be sent to the capital, however, the Faceless Man strikes again. Arya duels him one last time in the Riverrun godswood and kills him. Lord Blackwood helps her escape and they take shelter at High Heart, where the Ghost propesies their futures. After a final peaceful night atop the haunted sacred hill, they go their separate ways.
King's Landing
Tension remains between Queen Cersei Lannister and Jaime after her destruction of the Sept led to the suicide of their last child. However, Cersei and her Hand, Qyburn, have sought to stabilize the kingdoms, naming new Wardens (Randyll Tarly in the South, Harlan Dondarrion in the East, Wyman Manderly in the North and Tytos Brax (Rick Hoffman) in the West) and refilling the Small Counsel with the likes of Randyll Tarly and the unofficially captive Wylis Manderly (Olafur Darri Olafsson).
While Daenerys' arrival is concerning, Qyburn unveils his Scorpion Bolts and other creations to combat the invaders and sends Jaime, Lord Brax and the Tarlys to retake Highgarden. The sudden return of Cersei's Aunt Genna shakes up the court. She seeks to mother a neice she sees as acting irresponsibly, and urges her to focus on diplomacy to secure the support of the noble houses. Of particular concern are Oldtown and Dorne, who have yet to swear to Cersei. Qyburn is sent to Oldtown and two Queensguard knights sent to Dorne, as it is known Princess Arianne is "prone to the sway of dashing young men".
The noble houses of the Reach side with Randyll Tarly against Olenna, making the siege of Highgarden less of siege and more of a stroll. Jaime gives the Tyrell matriarch a merciful death, but not before she reveals it was her who killed Joffery. Jaime bonds with Dickon Tarly over their similar paternal situations, but the noble young soldier dies beside his father when cowardly Lord Brax abandons him in the loot train ambush. Bronn, Jaime and the Lannister army successfully repel the invaders at great cost of life., thanks to Qyburn's plans. Bronn is named castellan of Highgarden until the war is over and a new lord named.
Back in the city, Euron Greyjoy is made Master of Ships and begins to court the Queen, quickly becoming a favorite of the people with his wild and theatrical charisma. When Cersei realizes she is pregnant and refuses to seek a medical termination, as Genna suggests, it is decided she must marry. Jaime returns, devastated and confused, to see his sister marrying Euron Greyjoy.
Oldtown
Beginning work at the Citadel, Sam befriends the mysterious acolyte Alleras (Letitia Wright) while Gilly and Little Sam are taken in by Ser Gunthor Hightower, the popular and dashing captain of the Oldtown Guard. After meeting Jorah Mormont in the sick bay, Sam and Alleras go against orders and secretly treat his greyscale under the cover of night, using forbiddon methods recorded by Qyburn during his time at the Citadel. When Jorah is cured, he begs support for Daenerys from Ser Baelor Hightower (Cary Elwes) who rules the city, as his father Lord Leyton has not left the Hightower for ten years. Baelor declines to pledge, but sends Jorah with his youngest brother Humfrey to buy sellsails from Jorah's own ex-wife in Lys.
For his effort in the cure, Sam is made acolyte and studies religiously. Before Jorah leaves, he gives the knight his family sword, Heartsbane, in exchange for a pledge to convince Daenerys to go North to fight the Night King. Seneschal Ebrose takes Sam under his wing, but chides him for his belief in things like White Walkers. The maesters are working to build a future without magic or mystery, a world that man can control. All is going well until Sam learns of his family's fate. Despondent that he pledged their sword to the woman who murdered them, he disappears alone into the misty cobblestone streets of Oldtown.
Dorne
By the time the Sand Snakes and Greyjoys return to Sunspear, Princess Arianne Martell (Geraldine Viswanathan) has unexpectedly returned with her lover, Ser Gerold "Darkstar" Dayne (David Casteneda), to claim her birthright. This comes as a surprise to all, as Arianne was viewed by most as a thoughtless, party-loving sociallite. This will prove to be a dangerous underestimation, as Arianne refuses to support Daenerys, sending back only those troops loyal to Ellaria. She befriends Yara, but offers a threatening reminder of what Dorne did to the invading Targaryen queen during Aegon's conquest - Shooting her and her dragon out of the sky.
Arianne next welcomes two knights of the Queensguard - Ser Arys Oakheart (Oliver Jackson-Cohen) and Ser Osmund Kettleblack. It becomes clear that Darkstar, a bitter man who drinks only lemon water and is fiercely jealous of the legend of his famous cousin, Ser Arthur Dayne, has effectively sold her off to Cersei for a place of his own on the Queensguard. Instead, Arianne seduces Ser Arys and turns the tables on her former lover. Ser Osmund is killed and Darkstar flees into the desert. With Arys and Rolland Storm (Clive Standen) at her side, she declares Dorne a free kingdom once again.
FINALE
In the final scenes, we find a glass candle lit in the lord's chambers atop the Hightower. Through the magical flaming dragonglass, we can see all our heroes across Westeros: Jon, Tormund and Obara lead a party of Wildings, Red Priests and the Brotherhood beyond the Wall. Sansa welcomes Lord Tytos Blackwood to Winterfell while Bran is tormented by more dreams. Tyrion sleeps in the dungeons in a cell, next to fellow prisoner Melisandre. Daenerys and the wounded dragons limp into Castlery Rock. Genna holds back Jaime as Cersei and Euron are married by a Red Priest in the ruins of the Sept. And as they dance the shadows dance with them...
All this is seen by Lord Leyton Hightower (Timothy Dalton), at last revealed in the final shot, imploring his daughter that they must contact Bran, for "the song of ice and fire has begun".
Hope you enjoyed this! Please, leave any comments you have in the thread below, all feedback and discussion is greatly appreciated! Who knows, if my screenwriting career takes off, one of these days I may yet get to write in Martin's world for real! Until then, it's just fun to imagine.