This story relies completely on the canon of the books to illustrate what really may have happened to Snape and Moody, where they may have disappeared to, and why they may be returning nineteen years after Voldemort's defeat.

Rose Weasley returns to Hogwarts as a teacher and realises that she knows nothing about that war her parents had fought in. Based on the premise that Snape and Moody have survived, and narrated with post-war generation's point of view.

Young Severus Snape and Bella Black in a Muggle car.

A freshly graduated Severus Snape is brewing banned potions at Spinner's End.

There can be more in a caretaker than meets the eye: Squibs are people too.