I have an interesting possibility. What if the spell didn't make Parson loyal to Stanley at all, but actually made him loyal to Wanda?
Note here that he didn't actually obey Stanley until Wanda told him to: http://www.erfworld.com/book-1-archive/?px=%2F019.jpg
If Wanda is planning to overthrow Stanley, as has been speculated, then this could be a big reveal for book 2.
Or I could just be waving some trees about....