So for the purposes of this prompt, time travel mechanics work like this: When Noctis goes back in time, he remembers everything that transpires later, but none of his companions remember anything beyond the beginning of Chapter 9. However, if he changes anything drastic, the future can change with it--although Noct doesn't realize this until it's too late.
Upon returning from his crystal slumber, Noctis realizes that he missed his chance to ever tell Prompto how he felt about him. Desperate to have some closure, he asks Umbra to take him back in time to before the events at Altissia. There, he does his best to sweep Prompto off his feet with a romantic confession and some deeply emotional sexytimes. Prompto is confused at Noct's sudden change in behavior but he's not exactly going to complain. Then, after allowing himself this one brief escape from his fate, Noctis returns to the future.
Bonus: When Noct returns, things are no longer as he left them. Up to you how Prompto knowing about Noctis' feelings changed the outcome of the second half of the game.
Noctis/Prompto Time Travel
Upon returning from his crystal slumber, Noctis realizes that he missed his chance to ever tell Prompto how he felt about him. Desperate to have some closure, he asks Umbra to take him back in time to before the events at Altissia. There, he does his best to sweep Prompto off his feet with a romantic confession and some deeply emotional sexytimes. Prompto is confused at Noct's sudden change in behavior but he's not exactly going to complain. Then, after allowing himself this one brief escape from his fate, Noctis returns to the future.
Bonus: When Noct returns, things are no longer as he left them. Up to you how Prompto knowing about Noctis' feelings changed the outcome of the second half of the game.