Percy Jackson's Twin Sister

When Percy was twelve him and his sister were attacked. When they took their mother far from home along with Grover to camp half-blood the car was knocked over. Then everyone except his sister, Darya got out. The car fell off the cliff into the ocean. Percy thought she was dead as did Grover and Sally but she didn't. Soon she meets her father and the other gods. Unlike Percy ALL the gods liked her. Even Aries! Darya was later at age 14 (during book 3 in Percy Jackson series) asked by Chaos himself to join his army as commander and what happened to her you have to read to find out.