Levi x Mikasa - Forbidden?

This is a modern!highschool!AU where the cast of SnK attends Survey High. Mikasa Ackerman and her adopted brother Eren Jaeger don't always get along, but they're still the best of friends along with former child prodigy, current certified genius Armin Arlert. When their usual calculus AB teacher goes on extended leave, the kids get a long-term sub — Levi. Rumors spread about Mikasa being related to the mysterious Levi Ackerman even though she is sure they are completely unfounded. Does Mikasa really hate the new sub as much as she wants to believe? Is his rude apathy as founded as it seems? Doubtful on both accounts.