Personally, I think there should be a book where Nico and Will go down to Tartarus as hinted in the Trials of Apollo series. I think Jason should accidentally be brought to life. That way it's not cheating death. I must admit, Jason is not one of my favorite characters but it still broke my heart when he died. I would love to see him and Piper together again. Nico would be the perfect person to bring him back since they had a close relationship. Jason dieing honestly ruined the entire series for me. So, I would love for him to come back to life even if it was an accident.