In the period between Arthur’s death and her marriage to Henry VIII, Catherine of Aragon had grown very close to, even dependent on, her new confessor, Fray Diego Fernández, whom she described as the "best confessor that ever woman in my position had, with respect to his life as well as to his holy doctrine and proficiency in letters". She said that he "was serving me faithfully, giving me good advice and a good example, and nothing grieved me more than that my poverty did not permit me to reward him as he deserved."
However, not everyone at court liked the new confessor. Fray Diego had gained such a hold over the princess that she obeyed him in everything. Here's an example:
Fuensalida describes Fray Diego Fernandez as a monk having neither learning nor appearance, nor manners, nor competency, nor credit. He was light, haughty, and licentious to an extreme degree. On another occasion the ambassador calls him a "pestiferous" person who could not too soon be removed from the presence of the Princess. But, on the other hand, he was young, and does not seem to have been deficient in aptitude for the despatch of business, as he discharged not only the duties of confessor but also those of chancellor to the Princess. He gained her confidence and her affection. The most effectual weapon in the hands of a priest is the belief of others that he is the dispenser of rewards and punishments in future life. Of this Fray Diego made a most unscrupulous use, declaring everything to be a mortal sin which displeased him, however innocent it might be.
Fuensalida gives us one striking illustration. King Henry had asked the Princess Katharine and Princess Mary to go to Richmond, where he intended to meet them. When the Princess Katharine was ready to start, the friar came into her room, and said to her, "You shall not go today." The Princess, it is true, had vomited that night, but was again perfectly well, and the distance she had to travel was at the utmost less than one league. She therefore protested that she was not ill, and did not like to be left behind alone. The friar, however, overruled her objections in a high-handed manner by his categorical command, "I tell you that upon pain of mortal sin you shall not go today." The Princess, "not daring to displease him," had no choice left, and underwent the humiliation of telling the Princess Mary, who had been waiting for her more than two hours, that she was unable to go.
It is easy to imagine the feelings of the English gentlemen who, having been appointed to escort the two princesses, rode off with the Princess Mary alone, leaving their future queen behind in the company of a young Spanish monk of bad repute and a few servants, one of whom had arrived by mere chance. They could not have been deceived by her pretext of indisposition, as they had seen her at mass and at dinner in perfect health. When, on the following day, she went to Richmond, accompanied by no other living creature than three women on horseback, her maestre sala, a chamberlain, and Fray Diego, King Henry was so much incensed, that for several weeks he did not take the slightest notice of her, although during that time she really fell ill. "May God forgive me," exclaimed the ambassador, "but since I have known so well the affairs of the Princess' household, I acquit the King of England of a great and very great portion of the blame which I hitherto laid on him, and do not wonder at what he has done, but at what he does not do."
Fray Diego made the infatuation of the Princess a means of obtaining pecuniary advantages. She was living in absolute poverty, and her father had strictly forbidden her to sell any portion of her plate and jewels, which were to be given in part payment of her dower to the King of England. In spite of these injunctions she sold some plate, and would have sold more had she not been prevented by her servants, in order to "satisfy the follies" of the friar; and, unmindful of her own wants, she employed the money in buying books and other things for him.
Further reading:
Calendar of State Papers, Spain: Supplement to Volumes 1 and 2: Queen Katherine; Intended Marriage of King Henry VII to Queen Juana