David Salaman is what is known as an Exchanger, a person who has the power to instantly transform whatever he/she comes in contact with into anything that has an equal value.
When David was young, he believed that everything in the world was like Exchanging in the sense that it can only be exchanged for something that has the same value, until one day he lost everything and gained nothing in return, now he is trying to break all of the mortal laws and obtain all that he has lost without giving anything in return a feat believed to be possible only for a god.