When she first encounters Sir Gareth in book 4 of Le Morte d'Arthur, Lyonet believes him to be a kitchen boy and treats him with all the disdain one might expect a great lady to show towards a servant in a feudal society. Although he is helping her, Lyonet behaves, at least verbally, as Sir Gareth's antagonist. She even derides him in the presence of his opponent, the Green Knight, Sir Pertolope. Later, she frustrates his plans in a more practical manner when she prevents him from consummating his relationship with her sister, Lyonesse.
Lyonet's power comes principally from Gareth's chivalry and her bullying. The power of the fairy lady over Lanval, by contrast, is that of enchantment in every sense of the word. For the sad, lonely knight, the appearance of the most beautiful woman he has ever seen, surrounded by the magnificence of her court, is a dream come true or perhaps happiness beyond his wildest dreams. Unlike Lyonet, the fairy lady treats Lanval with respect and generosity, as well as showing her love for him. However, the fact that Lanval cannot adhere to her single stipulation of secrecy shows that her power over him fades in her absence, perhaps because he does not altogether believe that she is real.