Heroes of Olympus By Rick Riordan
Lost Hero: starts with Jason, a demigod with no memories of where he came from ending up with Piper and Leo, Two other demigods, who seem to have their memories modified to remember Jason. They end up in Camp Halfblood and meet Annabeth who seems to have lost her Percy. After lineages are sorted out they must travel across the country to save Hera.
Son of Neptune: starts with a familiar narrator, Percy, having no memory of who he is or where he is from except someone named Annabeth is important to him. He finds a camp of kids descended from the Roman gods and goddesses and must help them recover the lost standard of the Roman legion. He teams up with Frank and Hazel and Nico makes a cameo.
Mark of Athena: Both groups of campers team up head to the seat of power in ancient Greece, on the way relationships blossom and chaos abounds. Their main goal is to defeat Gaia but Annabeth is distracted by the Mark of Athena, a trail of clues left by the goddess Athena to test her children. This book was fantastic and the year wait between Mark of Athena and House of Hades was very painful.
House of Hades: Percy and Annabeth fight their way across Tartarus trying to close the Doors of Death while the others try to find the doors in the mortal world. Hazel is amazing in this one.
Blood of Olympus: Reunited at last the final confrontation between the demigods and Gaia is in full swing. Friends are lost and sacrifices made leading to one of the best series endings I have encountered in quite some time.
The Heroes of Olympus books were better constructed than the Percy Jackson and the Olympians series. There were more narrators with their own tales to tell in the world of reconstructed Greek and roman myths, even if a few of the kids blended together at times. There was more drama, every demigod has emotional trauma they are working through from their past that defines them. Hazel had died once already, Leo believed he killed his family with fire, Frank struggles for identity issues and a severe magical sign of his own mortality, Piper acts up to get her father’s attention, and Nico is not only displaced from time but struggles with his own sexuality. All these characters feel they are flawed or broken, but the tragedies in their past make them stronger and deeper characters. Leo will always stand out as an all-time favorite character for me. It is also neat they all are from different cultural backgrounds and nationalities, Riordan made great choices to try to include as many different connections with potential readers as possible.
You can find out more on the series and the Author at http://www.rickriordan.com/