The Lost Hero

Jason wakes up and finds himself in a camp with a "girlfriend" he has never seen before. His has no memory, but there are plenty of people that want to kill him. He realizes he (along with his "girlfriend" and one other student) are half-blood descendent of a Greek god. However, the gods are not talking with people these days. They make it to the half-blood camp. Unfortunately, there are others that are trying to destroy the world. He gradually finds out a little bit more about his true identity. He is a "Roman" half-blood on an "exchange" to Greek land. (Percy Jackson is on a similar reverse exchange.) He actually does like the "girlfriend" Piper, though discovers that she is the daughter of Aphrodite and a famous action star. They go on a quest, battle a bunch of bad guys and finally reach a conclusion, setting up things for the next book.