the Real villain of this
Prior Philip he has no loyalty to anyone, just HIS cathedral.
He is willing to accept Wallerian's help in becoming prior, but feels that Wallerian is evil to want Philip to help him become Bishop.
He turns on the Bishop 's plan just because he thinks he can make a better deal with the Hammelieghs, and in the book he is very satisfied that "a lowly monk who didn't even know to wear a clean robe to see the king" was able to outsmart two Bishops. And he knew that the Earl 's kids were living in the castle, he didn't warn them or move to protect them from William.
In the book he wanted Stephen to be king, not because he thought it was the right thing but because it would be better for the church, and of course him and his Priory. Later when the king does not rule in Philip ´s favor he is thrilled when Stephen loses the Battle of Lincoln, now he is even putting His Priory over the church as a whole.
When he decides he wants Jack as a monk he is quick to use Jack's fight with Alfred as an excuse to force Jack to become a monk, even though Jack has turned down being a monk before and has no desire to be a monk.
Philip is a sociopath, a narcissist, or just a plain old the end justifies the means villain.