This story takes place in an alternate timeline where Margaery Tyrell escaped the destruction of the Sept of Balor and managed to ally herself with Daenerys Targaryen.
"I am Daenerys Stormborn of House Targaryen, the First of Her Name, Rightful Queen of the Andals and the First Men, Protector of the Seven Kingdoms, the Mother of Dragons, the Khaleesi of the Great Grass Sea, the Unburnt, the Breaker of Chains." Daenerys addressed her army, which stood several tens of thousands strong. Made up of some of the legendary and fierce soldiers from the other-side of the Narrow Sea. Dothraki, Unsullied and most importantly, Dragons. "And this is my ancestral home, Dragonstone. To all of you who have stood by me, who have borne witness to the power of the dragon, I promise you this place is the first of many great castles we mean to take back from those who have usurped my family of the Iron Throne."
"We stand at the precipice of our goal, the seven kingdoms are within our reach and we will rescue my people from the greed and cruelty of those that betrayed my family and sought to claim these once great kingdoms from themselves. Those of you who continue to show me loyalty shall be repaid one hundred times over. For as you know, I am not only a strong Khaleesi but I am also fair and just. Which is why I wish to present to you, Margaery of House Tyrell." Dany continues her speech before signalling for the former Queen of Westeros to emerge from the front of the large crowd to join her atop the platform she was using to address her great army. This causes hushed murmurs to break out among the crowds, for even those among the Dothraki knew Margaery as the former wife of King Tommen, son of the man who usurped the Targaryen throne.
"Calm yourself my friends, my bloodriders. I know many of you, even those among my most trusted council may be wary of Lady Margaery." Dany says while casting a quick glance towards Tyrion Lannister who returns her look with a subtle and yet unmistakably concerned expression upon his bearded face. After all he witnessed first hand the opportunistic nature of the Tyrell's, who quickly went from open rebellion against the Iron Throne to marrying into the royal family.
"Yet I assure you, she is not our enemy. She is our ally. The Tyrell's stood by my family when the usurper rebelled against them and she has just as much reason to stand against the Lannisters as we do. I ask all of you to trust me once more, for I swear I would never lead you astray. I have led you across the Black Salt Sea and now I ask you to welcome Lady Margaery and House Tyrell into this great army as I have welcomed her into me-Ah, into, um.." The usually confident, naturally gifted orator stumbles uncharacteristically as her face is invaded with a slight, near imperceptible flushness.
"...Together we are strong and together we will tear down the stone houses of our enemies and fulfill the promise the Great Khal Drogo made to me before the Mother of Mountains. Are you with me?! Now: and always?!" Daenerys hurriedly moves along to finish her speech, drawing a massive uproar of approval from her forces. The silver haired Khaleesi basks in the cheers and cries of support for a few moments before turning to walk back towards her castle, with Tyrion and Margaery following closely at her side.
"That was magnificent Your Grace, I have only heard tales of your prowess as a leader but to hear you address your people with my own ears, surely you are blessed by The Mother herself." Margaery flatters, displaying the silver tongue that has gilded her through the high courts of the Seven Kingdoms for her entire life.
"Yes, yes. Our Queen inspires a loyalty unheard of among the high lords and ladies that you're used to cavorting with Lady Margaery. Perhaps you should take note, I'm sure all that time spent among my wretched family has twisted your view of how a ruler should behave." Tyrion replies impatiently, casting a distrustful look towards his new "ally".
"Oh, I believe you'll be pleasantly surprised by how I view things Lord Tyrion. Your sister Cersei and nephew Joffrey were cruel to be sure but I think you'll find the people of King's Landing will be delighted to see me alive and well once we seize the capitol. Perhaps I will even convince them to love you in the same way, if I remember correctly they were chanting from your execution the last time you stood inside the Red Keep. I would be happy to do so of course, we are trusted allies after all." Margaery responds with a well practiced smile, the true intention of her words only faintly visible through her beautiful blue eyes.
"Your loyalty to your allies is well known my lady, I shall be forever grateful for your families assistance at the Battle of the Blackwater. Although I can't imagine the Baratheon's share my gratitude. You were originally allied with them, even married to Lord Renly were you not?" Tyrion replies, the intentions behind his words much less thinly veiled than those of Lady Tyrell.
"That's quite enough Lord Tyrion. You are my hand are you not? Then I expect you to show the same respect to Lady Margaery as I have." Daenerys interjects, growing increasingly impatient at the poorly disguised bickering taking place amongst her council. "Now if you'll excuse us my lord, we have urgent matters that require our attention."
"...Of course Your Grace: Perhaps I could assist in such matters? As you say, I am the Hand of the Queen." Tyrion Lannister replied after a brief moment, clearly concerned by the trust and confidence that his Queen was so quickly placing within a woman they would have considered an enemy mere weeks ago.
"That will not be necessary my lord, I am much better: equipped to help our Queen in such matters. Surely you have other duties that require your capable hands?" Margaery answers in place of Daenerys, drawing another look of annoyance from the half-man hand.