William suffers from a resentment, inherited from his father, that he actually has to work for a living. He sees himself as the equal of everyone and better than most.
He has no interest in becoming popular or part of a clique, he prefers total independence.
He believes that he can persuade anyone to do whatever he wants them to do. However, he then commits himself to support them to achieve success.
As an example of this ability, he appointed himself to be squire to William Montacute. the Earl of Salisbury. The Earl declared however that two people having the same name would be confusing and so William renamed himself… Piers.
He watches everyone, continually accessing their strengths and weaknesses, storing the information away for a time when he can use it to good effect.
His father thought that being in Occitan with the Black Prince might give him the opportunity to marry the daughter of a southern lord and he never ignores this opportunity for advancement, but he gradually acquires ambitions on a much higher plane.
His skill is that few people are aware of his ever-changing evaluation of the opportunities available to him.