The Lily of Valois
Joanna was kept hostage by the Mendoza family from 1465 to 1470, and by Juan Pacheco from 1470-1475. In 26 October 1470, she was engaged and then married by proxy to the Duke of Guienne, and again proclaimed as legitimate heir to the throne. The duke died in 1472. There were many marriage negotiations in order to marry her to someone who could defend her succession. After a few unsettled arrangements, which included French and Burgundian princes, Joanna was promised in marriage to her maternal uncle, King Afonso V of Portugal, who swore to defend her (and his own) rights to the crown of Castile.
On 30 May 1475, her uncle Afonso V of Portugal married Joanna in Plasencia and prepared for the fighting. In 1476 Afonso invaded Castile. Afonso was defeated in the battle of Toro by Ferdinand I of Sicily, Isabella I's husband. After this, Afonso V tried to procure, without success, an alliance with Louis XI of France. In 1478, the marriage between Joan and Afonso was annulled by Pope Sixtus IV on account of their family relation. She was then forced to renounce her titles as Infanta of Castile, Queen regnant of Castile, and also as Queen consort of Portugal.
But what if La-Betraneja went to France to see Charles of Guyennne and married the Dauphin, Charles VIII.