You have already heard us talk about how Prince João had gone over to Castile and how he had been brought to join the king's court owing to his sister Princess Beatriz, who was the wife of Count Sancho. Thus it was that the king gave him Alba de Tormes, Manzanares el Real and other townships. Yet he did not enjoy quite the well-to-do standard of living that befitted his status, for his daily entourage never exceeded ten to twelve retainers who were always with him. Other noblemen, however, who had a strong liking for the prince because of who he was, greatly honoured him, showed him hospitality and kept him company both in his own house and on the way to the palace. Such men included Don Juan, who was the son of Don Tello, King Enrique's brother, who possessed ten times as many houses as the prince, the Marquess of Villena and Pedro Fernández de Velasco, who never failed going anywhere with a team of 150 mules. He also enjoyed the company of Juan Duque and his brother Ruy Duque, as well as of other worthy noblemen of the king's household.

When the King of Castile married Princess Beatriz, knowing that King Fernando was very frequently ill, they immediately began to fear that the prince would reign after King Fernando's death; they also began to be unsure of him and to arrange ways of preventing him from doing anything on his own account that the king did not know about.

Some of his supporters understood this situation and repeatedly drew it to the prince's attention, but, as a man who could never harbour malicious thoughts, he attached no importance to what they had to say. No sooner had the king ordered the arrest of his brother Count Alfonso than he also ordered García González de Grijalba to arrest Prince João in the prince's apartments. He ordered that the prince be told that he was not arresting him for anything which he knew to be against his, the king’s, service, but that he was afraid, now that King Fernando had passed away, that certain Portuguese would acclaim him king and would cause a disturbance in the country contrary to what was laid down in the treaties. Moreover, he should be held prisoner at the king's pleasure until such time as the latter was reassured about this.