Reincarnated

The houses at Hogwarts were created by two witches and two wizards. Salazar Slytherin, Helga Hufflepuff, Gorbic Gryffindor, and Rowena Ravenclaw. They each created the houses out of their own characteristics for those who come to Hogwarts in the future. They left the Sorting Hat behind to sort future students into the houses. The four knew their would be more conflicts ahead, so they did a enchantment that costs them their lives.

Centuries later four witches go to Hogwarts. This is after the war with Lord Voldemort, but still in the age where Harry Potter is an Auror and has children with Ginny Wesley. These four witches get separated into houses, going to on with their excitement of being in Hogwarts.

Then the nightmares start. Strange events start to happen. There's something out there threatening Hogwarts. The four witches must find out what's going on and why. They do it alone since no one likes to dwell on such things since the war ended nineteen years ago.

Nineteen years ago a war ended.

Now, a new one is in the making.