This is an idea for a Voltron: Legendary Defender AU fic. I can't promise that I will have time to write it myself, so treat it as a free idea to take on. Here's an overview.

The setting will be a galactic college, so whichever author takes this will have free reign to make Shiro either a student or a teacher(knowing the age gap between him and the other paladins), split up among it's buildings, which identify themselves as their own "academy's". Galra Academy holds the most sway among the svhool board, since at this point Zarkon is the primary financial supplier. Altean academy sits in ruin, three guesses why, and the other buildings are essentially kept firmly under Galra Academy's heel, save for one, Paladin Academy. Paladin Academy only ever has ten students: The Lions(who will be receiving the Mecha Girl treatment for the purposes of this story) and their Paladins. This is where the story begins. (The Lions' names will be their colors, for simplicity's sake)

Keith is the first to arrive, since Shiro asked him to come, and already makes his mark as a kind-hearted delinquent/bad boy when he pulls his knife on a couple of Galra boys causing Red some trouble. She in turn chooses Keith to be her Paladin. When Lance, Pidge and Hunk arrive, they don't do anything nearly as risky to become the Paladins of their respective Lions. The story then follows a pretty standard slice of life storyline for the rest of Volume 1(A Volume in this story coincides with a Season of the show), then Black sparks a romance subplot when she shows interest in Keith, to Red's dismay. Shiro disappears at the end of Volume 2, causing Keith to become more erratic at the start of Volume 3(I imagine there being quite a few "Confrontation in the rain" scenes between Keith and Galra students who may be connected to Shiro's disappearance). Black ends up being the only one able to calm Keith down enough to listen to reason, sparking his side of their romance(Red uses Lance as a rebound, but it eventually turns into a relationship, though what kind, you can decide). Allura then transfers into Paladin Academy, upon Blue's request, and a new status quo is formed... until "Shiro"(Kuron) arrives and Keith transfers into Marmora Academy(Black is a bit of a crybaby in regards to Keith leaving). Then comes the mystery subplot, with Keith Holmesing it up with Kolivan and later Krolia. Keith eventually comes back to Paladin Academy to call out "Shiro" as a fake, as he finds the real Shiro's body while investigating Lotor's underground (insert illegal thing here). After confronting Kuron and Lotor, a new status quo is reached, as well as the romance subplot between Keith and Black coming to a satisfying conclusion (until Volume 7).

Not that this needs to be explained, but the primary ship of the story is between Keith and Black(Bleith?), but as is normal in Slice of Life stories, there's more than one relationship. In terms of Lance, you could go with the classic Allurance/Lallura(whatever you call it) or you could follow the story's trend and ship Lance with Red(Rance?). I'd say everyone else is fair game.

Well, there's the overview. Any details, like class order, clubs, or school events/trips are free for you to decide should you choose to pick this story up. Please leave a review if you're interested in writing this, that way I know who to keep an eye out for in terms of this story popping up.