From Discworld & Terry Pratchett Wiki
Joshua Valienté is one of the main characters in The Long Earth. His mother, Maria Valienté, gave birth to him in strange circumstances- even more strange than the business with Jeremy Clockson. Like Jeremy, therefore, he is quite a recluse, enjoying the presence of what he terms the 'Silence'. Indeed, compared to Joshua, Daniel Boone was pathologically gregarious. He follows instructions zealously- the similarities are stacking up- and he looks down on others who do not prepare. He was brought up by an unusual convent of nuns, in that they prefer listening to Bob Dylan than the hymns of the faithful. He is quite a celebrity, in that people stop him in the street and go: "Joshua Valienté? You're him, aren't you? The weird one? With the Stepper? And the nuns?"
He demonstrates his usefulness during the events of The Long Earth, in that he and Lobsang embark on a top-secret mission to the depths of Long Earth for that most natural of reasons: to see what is out there, and whether it turns a profit.
He returns in The Long War having become husband to Helen Green and father of Daniel. Reluctantly coming out of retirement to aid Lobsang and Sally Linsay, he has another series of adventures culminating in his winning The Game against the Beagles but losing his arm as a trophy. It is replaced with a prosthetic.