Ciri helped Sally Jackson with a Greek monster problem and Sally didn't have the currency of her world, so she envoked the Law of Surprises. Desperate to return her debt, Sally stayed true to her word and brought the first thing she saw when returning home. Ciri half expected a painting, a chair perhaps, even hopefully some food. She never expected to be given a child. And a boy for that matter. So as the code states, she took the boy back to her home, Kaer Morhen. Geralt was reluctant to bring in the boy. He didn't want to burden any more children. After all, jobs for Witchers where dying off... litterally. But eventually he trained the boy and even went on to preform the traditional witcher trials, like the Trial of Grasses. Much like Geralt, the boy also went through extra mutations, though due to him not completely being human, it didn't effect his skin nor hair, well, not completely. At the age of 18 he returned to his home, and a war is brewing. A war between humans and monsters. (The prophecy follows Percy's brother's age, not Percy) I don't own Percy Jackson, The Witcher, nor any characters involved unless their an OC. Rick Riordan owns Percy Jackson and Andrzej Sapkowski and CD Projekt own The Witcher.