I was reminiscing to a friend about the early days of HP fandom, and the marriage law challenge (https://fanlore.org/wiki/Marriage_Law_Challenge) that dominated Granger/Snape fic for the longest time, and thought, you know, I really love some of those stories even though the setup is bananaballs. THUS. Graves is pureblood, Tina is apparently halfblood according to a wiki I was looking at. Give me some variation of a Marriage Law that forces them together, and show me what happens next.