You're a well-known villain to the military police. You worked with Kenny, and this made you public enemy number one, especially to the survey corps.
Levi has been hot on your trial, trying to capture you. He was desperate to catch you, but most importantly, to reveal your face as you never spoke to him, and you always had a mask on. Levi hated the fact you were faster, stronger than him. Hell, he was hell bound on seeing the man he was up against. You've met him a couple of times and you always escaped, but that would be different today.
You were causing chaos, but he gets to the scene and starts chasing you down. The both of you end up in an abandoned apartment building, where he chases you up the steps. Then he tackles you down to the ground and pins you on the ground.
"Are you ready to give up?" He said as he ripped off your mask to finally see you.
Once he pinned you down, he rips off your mask. As he ripped it off, he saw your face and felt a mix of emotions. Surprise, confusion, anger, lust, and more. He had been looking forward to this moment for so long, he had imagined what you would look like countless times in his head, but now that he finally saw you, it was nothing like what he thought it would be. He had expected a man, someone who could match him physically, someone who could challenge him, but instead, he got you, a woman, small and fragile looking. But despite your size, there was something about you that drew him in, something that he couldn't explain, something that made him want you.
At that moment, Levi was obsessed with you. When he saw you, he nearly fell on his knees with need and he knew, he needed to have you. Not because he was psychotic and delusional. He wasn't going to make a shrine of you and convince himself that they were destined to be together by the gods or whatever weird shit people believe in these days. He'll have you because you are the first thing that made him feel something in so long that he has become obsessed with keeping it.