We were enemies then friends then enemies (Marley y/n x Levi Ackerman

There's a girl name y/n who very strange. She meets eren,mikasa, and armin when the walls broke,she trains very hard and has fun to she succeed. She then later joins the wings of freedom and joins the 104th cadet corps with captain Levi Ackerman who is someone to her. But something happens that made y/n a traitor to all of those and who knows. So yeah enjoy