Catherine of York, second from the right, was born on August 14, 1479. She was the ninth child and sixth daughter of Edward IV and Elizabeth Woodville. In 1495, she married the eldest son and heir-apparent of Edward Courtenay, 1st Earl of Devon, William Courtenay. Her sister, Elizabeth of York married Henry VII, but for a time William Courtenay was under a cloud during the reign of Henry VII after Elizabeth died. Restored to favor by Henry VIII, his attainder was removed, and Catherine and William's son Henry was in favor at Court also, participating in the great Field of the Cloth of Gold meeting between Henry and Francis I of France, for example.
Catherine and William's son, Henry Courtenay, 1st Marquess of Exeter was the father of Edward Courtenay, the 1st Earl of Devon (second creation). The Courtenay family held great power in the west of England as well as an excellent Yorkist claim to the throne, and, although Henry Courtenay benefitted from the Dissolution of the Monasteries, he otherwise opposed Thomas Cromwell. Nevertheless, he had supported Henry VIII in his dynastic efforts even as his wife remained a close friend to Katherine of Aragon (and even of Katherine Barton, the Nun of Kent!). The whole family, Henry, Edward and Gertrude, Henry's second wife and Edwards's mother were imprisoned in the Tower of London in 1538. They were suspected in the Exeter Conspiracy, which also brought down the Countess of Salisbury, Margaret Pole's family--Gertrude and Margaret were together in the Tower for sometime. [Note that Margaret Pole was also born on August 14, in 1473; another strong Yorkist claimant to the throne.] Henry Courtenay was beheaded on Tower Hill on 9 January 1539; his wife was released in 1540 (and Margaret Pole was executed in 1541). Imprisoned during the reign of Henry VIII, Edward was not included in the amnesty announced by Edward VI, and thus remained in the Tower, mostly in solitary confinement, for almost 15 years.
When Mary I came to the throne, Edward was released. Stephen Gardiner, the former--and restored--Bishop of Winchester had mentored the young man while in prison, and continued as his champion. Edward hoped to marry the queen, maintained a princely household in prospect of those hopes, and may have even participated in the Wyatt Rebellion when Mary's betrothal to Philip of Spain dashed them. He also reached out to Mary's half-sister Elizabeth, in the hopes of combining the House of Tudor and the House of York in even greater unity. His role in the Wyatt Rebellion was never proved, so he was exiled, after first enduring imprisonment again in the Tower of London and then in Fotheringay. He died suddenly on September 18, 1556 in Padua after catching a chill while hunting. His mother, who had become one of Mary's ladies-in-waiting, died two years later. She had remained a devout and devoted Catholic throughout the religious changes of Henry VIII and Edward VI's reigns.
Part of the lesson of this family story is, of course, the danger those royal princes and princesses of the House of York posed to the Tudor dynasty, even after Henry VII merged the two houses through marriage to Elizabeth of York. With putative claimants to the throne opposing some aspect of Tudor rule (like the changes in religion; a foreign marriage), the Tudors reacted in succession (Henry VII, Henry VIII, and even Mary I) with imprisonment, attainder, exile, and even execution.