This story is a sequel to The Princess and the Sentry

Flash has a problem. He doesn't remember anything before waking up in the Crystal Empire's Military Infirmary. Apparently he has a girlfriend named Twilight Sparkle, and serves her brother, Shining Armor as a Private in the Royal Guard. He already hurt Twilight once. Now he's got the chance to right the wrong, after an impossible leap in military ranks and re-stationing in Ponyville as Twilight's personal Guard. But he's going to find out there's more to him than he ever remembered before.

This story is a sequel to Fixing Flashlight

Things get awkward for Flash and Twilight after a sleepwalking incident, and Flash gets memories of being completely human at the same time as being a pony. investigation takes him to Canterlot high to return those memories, and repay that world's Flash for setting them up.

Twilight is troubled by her new title and is constantly driving herself to sleep deprivation every night since her coronation. Princess Celestia is worried about her, so she sends a personal guard for her. Flash Sentry.
Cute moments, arguments, funny situations and romance are now in the life of the new princess. Until she is called to Canterlot because of a new threat to Equestria.
Oni Fire, a night pony devoted to his princess of the night. Twilight, Flash and White Fur will discover the key to defeat their enemies.