For years the underworld of San Cristóbal answered to a veiled woman called the Yellow Lady: small, still, speaking perfect Crescent, flanked by a dark-haired sword. She hired the company to rescue a poisoned Inquisitor as a test, and paid them in exactly nothing, which they have not forgiven and she has not apologized for.
She is Princess Rocío Sandoval, the King's near-identical twin. She wore her brother's face for the realm's sake when it was useful, and vanished when the Inquisition took him, because the Inquisition never knew the King had a sister. Diego, being Castilian, mistook her for the King at the unmasking. That mistake is the whole weapon.
If it frees my brother, then I will go. — "Words, your grace. Words."
She is impulsive, guilt-ridden, and permanently furious at being the spare heir, stood down from her own raid by her mother and her bodyguard on succession grounds. She knows where Schattenbruch is and says it is safe, a sentence Axel has learned to hear as an invoice.