Why not?

Sylvain begins writing in the notebook.

Archbishop Rhea will transform into a dog girl whenever she hears Sylvain Gautier say 'Sit, Girl' and revert to normal when he says 'Good archbishop'. While transformed, Seteth is the archbishop and no one notices anything wrong and believe she is Sylvain's dutiful pet. When transformed, her ears will turn into erogenous dog ears and she will grow a dog tail, thinking she is a dog capable of human speech and intellect, but adopting canine behavior patterns, and that Sylvain is her owner. As a human, Rhea will remember what it felt like to be a submissive puppy for Sylvain, and want to do it more, and willingly do anything he asks, even in human form.

Sylvain almost uses it then and there, but he is curious of Rhea's other fantasies. And watching her masturbate was kind of hot too. So he decided to write down something extra.

Sylvain Gautier can make a woman masturbate anywhere and any time by saying. "How are you feeling," followed by their name while rubbing his thumb and middle finger together in front of them. While they masturbate, they will have an erotic fantasy featuring Sylvain, which they will scream out loudly to. No one will find this behavior odd or worthy of note.

Having set that up, he decides to wait for another erotic fantasy before making the archbishop his pet...