The wizarding world is steeped in tradition, and some things are sacred. Presenting your eligibility for courtship is something most purebloods and highborn take as a matter of course. Despite this, no one expects a decidedly different Harry Potter to throw his hat in the ring. Let alone that he'd register as a consort not a lord. Sociopath!Dark!Blood-mage!Harry

Harry isn't protective- he's possessive. Combine that with a steady influx of creature instincts and a sudden betrayal, and Harry isn't playing nice any more. At least, not with the wizards. Dark!Powerful!Vengeful!Harry. New School/academy.