Though he has no need to worry about money, he has no interest in simply managing the accounts of centuries of accumulated Swift wealth, nor in overseeing the operations of the bank the family controls. William wants to create things, to build, to make his mark on the world.

William is the more sceptical of the siblings, and has difficulty accepting his legacy, even when faced with incontrovertible physical and visual evidence. Despite whatever bickering he might engage in with her, he loves his sister dearly and is quietly proud of her independence and her accomplishments.

Though older and the man, William realises early on that Tamara is the more capable magician, and more painfully, better able to deal with the terrible changes wrought upon their lives by their inheritance.

In the aftermath of his grandfather's death, William grieves in his own way, attempting to keep a perspective upon the chaos in their lives. He holds firmly to the tether leading back to normalcy, to their lives before they discovered their destiny, and wants nothing more than to return to that state.

William is cynical and sarcastic, but this is balanced by a keen, self-deprecating sense of humour. He has a tendency to act before he thinks, and so finds himself grateful for the presence of his more even-natured sister.