Section I: May-August 1514
St Germain-de-Laye, May 1514
They don’t make the most prepossessing of couples as they emerge from the chapel door, blinking in the bright May sunlight.
Oh, the groom is striking enough. His complexion might be a little swarthier than is held to be ideal, his nose a little too hooked, but his height, shapely turned calf and the lithe controlled energy he carries himself with, more than make up for that.
The young woman on his arm, however, only suffers by comparison. She might be glittering in silver damask embroidered with dark blue fleur-de-lys, and wearing a headdress encrusted with tiny chips of sapphire, but not even the richest fabrics in Christendom can hide her short stature, her weak chin, or her hunched, twisted shoulders. The young Duchess of Brittany and Valois is not, nor has ever been, the kind of girl chroniclers fete for their beauty.
But then, she doesn’t have to be. Claude of France’s lack of looks don’t matter. Not when she is the greatest heiress of her generation and brings her husband all of Brittany as her dowry.
Brittany, after all, is the reason her father, King Louis XII of France has arranged this match in the first place. If the only thing recommending Claude were her royal blood, she’d have been married off abroad, the way her younger sister Renee, still a child in the nursery, will be one day. But Brittany is too grand a prize to let slip through one’s fingers. As such, the young man at Claude’s side, handing her into the litter and brushing her cheek lightly with his lips as he does so, is her father’s cousin and heir, Francis, Duke of Valois.
In Salic Law-governed France, it is he who will sit the throne after Louis. Claude will be little more than a vessel for him, a trophy at his side. As his Queen, she will lend his rule legitimacy in the dynastic sense; acting as the living, breathing link between the old dynasty and the new. God willing, she will also give him a son: a son to rule both France and Brittany, thereby completing her father’s long-held dream of merging her mother’s independent Duchy with the French Crown.
Claude settles herself back into her cushioned litter, only years of royal training stopping her from groaning in relief as the padded fabric behind her soothes her aching back.
Beside her, Francis spins on his heel as something moves in the corner of his vision. Sportsman’s training coming to the fore, he snatches the sprig of heather from the air and raises it to his lips, before tucking it into the brim of his feathered hat and blowing a kiss to the fair-haired girl who threw it.
The crowd goes wild, cheering all the louder as Francis mounts his horse, preparing to lead the Court in his and Claude’s wedding procession.
Even as they shout acclaim, however, the experienced matrons in the crowd are eyeing Claude’s waist, hoping and praying it won’t be long before their young Duchess grows stout with child.
They don’t say anything. They don’t need to. Claude is a woman too. Some things transcend the social strata, no matter how wide the gulf in rank. Closing her eyes for a brief moment, Claude adds her prayers to theirs.
“Sweet Jesus, let me quicken soon. In your Mercy, only let me quicken.”
**** **** ****Fortunately, Claude’s prayers – and those of most of France – are answered in what is, relatively speaking, the blink of an eye. Francis’s seed must catch on their very wedding night, for she swells with child within weeks, prompting her young husband to show her off at every opportunity, crowing with pride at this all-too-obvious sign of his virility. 
“A boy for France!” he tells anyone who will listen, over and over again, “You see, my wife and I know our duty. We’ll have a boy for France before the year is out!”
In the cloistered, sycophantic environment that is their country home, whence they have retreated – Francis for the hunting, Claude to escape the blistering suffocation that is Paris in the summer heat – no one thinks to point out that, as there are only five months left in the year, that is actually impossible. Their household simply fall over themselves to assure Francis that his coming child will be the lustiest boy France and Brittany have ever seen.
And then the news comes. Claude’s father has made peace with the young King across the Channel, Henry VIII of England. He has pledged himself to marry Henry’s teenage sister, the Lady Mary.
The Duc de Longueville has embarked for England to stand in King Louis’s place at a proxy wedding and Francis and Claude are being called to Court to head the new Queen’s welcoming party.
 This is the first, minor POD. Judging by the birth date of her first child, Claude didn't fall pregnant until about late November 1514 OTL. Here, she is sufficiently far along as to be showing by the time her father's new bride arrives in October. The other, more major POD, for which this thread is named, will follow in a couple of chapters' time.