I don't have much for this idea, but since there's interest, basically here's what I want to do:

Explore how the four's friendship began and their journey as they build Hogwarts and eventually their split starting with Salazar's departure. Obviously we're delving into headcanon territory here so anything goes. Personally this is how I see the characters and their relationships, but we don't have to use all of it if the players have other preferences.

Godric and Rowena like each other; though Godric's impulsiveness and the way he tends to jump into situations without thinking twice drives Rowena crazy, she has to admit his bravery and how nothing seems to scare him is something to admire. Godric, on the other hand, likes how smart Rowena is, and not just because she has bailed him from his jump-first-ask-questions-later disasters.

Helga and Salazar are also pretty close. Helga is basically the only person who can temper Salazar and his sometimes violent tendencies. She's his anchor and the one who keeps him grounded, the one who always brings him back into the light when he drifts too far into the darkness. She sees goodness in him when everyone else has given up on him. Salazar is prideful and doesn't care for most people, but Helga is a bit special to him - she's his one weakness. However, this still isn't enough to prevent the fracture that eventually happened between the four friends after the school was founded, nor his hatred for Muggle-borns.

Rowena admires Salazar's ambition and cunning, and he admires her brilliance, too. They both know together they can achieve world domination, which is something Salazar likes to tempt Rowena with, but Rowena is not interested in that.

Godric and Salazar started out as best friends despite clashing later. Godric and Helga also share a pretty much respectful, drama-free friendship - and so do Rowena and Helga.

Character Claims:
Godric Gryffindor - Sailor Pluto
Salazar Slytherin - OPEN
Rowena Ravenclaw - Sailor Mercury
Helga Hufflepuff - Addelyn

If you'll allow me to, I would like to claim Godric. I'm putting up my submission for SAO right now I promise.

Fineeee, you may have him