She's dark hair and dark eyes and dark wit. There's lightning on her tongue and a cold frostiness that can quiet Joffrey with only the tiniest sound. Instead of Westerosi Southern dresses, there are Essos' finest sheer dresses and tight, practical adornments of the Sand Snakes. People call Myrcella Baratheon strange, dangerous, cruel, yet they call her modern, gentle, kind too. Her mother cannot abide her presence, and her father can barely keep his wits about him around her.
Myrcella is the eldest child of Robert Baratheon, and she does whatever the fuck she wants.
She's long curls and daggered hair-pins and sharp nails painted black with poison that she'll swipe across the face of any that try to accost her as she roams Kings Landing, White Cloaks far off in the Red Keep trying to make themselves believe she hasn't already escaped from her room already. The cracks in the side of the Red Keep, gouges from dragons poorly filled are her ladders, and years of climbing it make her more, if not equally skilled to Brandon Stark. And when she's not climbing and exploring and whipping the poor men of the capital into shape – delicately and regularly marking those that would force themselves upon a woman with those poison nails, who with the horribly-scarring marks would be looked down on in disgust and hate and scorn, murder in their eyes for the innocents they had devoured – Myrcella is the perfect Lady.
They call her Queen long before Tommen names her Regent.
When Danaerys comes with her dragons, Myrcella is all charm and sickly sweet platitudes until it's revealed that Tyrion rules Meereen. Then Myrcella takes her kitten-hoarding brother and leaves the city she has called home for her entire life without fear, and all but drags her father – her brothers' father, her uncle, her father, the only one who loved her for who she was – to the Free City, half-way across the world.
Westeros can burn, for all she cares. But Kings Landing never forgets their Queen, and for the rest of time, Kings Landing would scar their rapists and would-be-rapists with blue lines from eyebrow to lip.
Myrcella is dark hair, dark eyes, dark wit; Myrcella has lightning on her tongue and wears clothes of warriors and whores; Myrcella is strange, modern, dangerous, gentle, cruel and kind; Myrcella is the Black Queen of Kings Landing, with poison on her nails and climbing in her blood.
Myrcella is a Baratheon, and she cries Ours is the Fury.