Just a heads up, guys, I'm going out of the country and don't know if I'll have Internet so if I disappear for long stretches of time, you'll know why. (I'll probably still be writing when I have time though.)
Levi is not a fool.
He may not be well-educated, he may not be able to multiply large sums in his head or read through treatises quickly without stumbling, but he has intellect; he is shrewd. He knows how to pick his fights, when to pull out his knife and when to run; how to remain unnoticed, how to stay out of the Military Police's way, all the back alleys and shortcuts through the underground streets of Sina. He can scavenge for food and pickpocket as easily as he breathes.
Even when he joins the Scouting Legion, he keeps that wit about him, that sense of always knowing what to do and how to do it. He only argues with Erwin when it is necessary and follows orders to the very last detail otherwise. He may be blunt, rude, unfriendly, but he knows how to get things done and everyone who has been under his command respects him for that, at least.
So when he finds himself exhibiting the strangest behaviors around Petra Ral, when his palms turn sweaty and his heart beats faster when she is near, he instantly knows getting involved with a subordinate would be a very, very bad idea.
He tells himself this over and over, countless times, when she brushes his hand in the mornings by accident while handing him a cup of coffee, when she talks to him late at night as he sits at the dinner table doing paperwork, when he walks in on her changing one time, the pale flash of her skin the only thing he sees before he turns around and walks right out to the sound of her stuttered apologies (it is his fault, he should be the one apologizing, but he can't get that image of her bare back out of his mind).
He tells himself this even when he finds himself straddled to his bed, her legs wrapped around him, her breath hot on his neck and her nails sharp against his skin, and he thinks fine, so he got involved: it's only physical, a way to relieve tension after expeditions, because he may be humanity's strongest soldier but he's still human. He is not stupid though; he has his heart kept firmly under lock and key.
But it happens again, and then again, even when expeditions are the farthest thing from their minds, and then it is no longer about the feeling of her body flush against his or the feeling of release he gets after spending a night with her; somehow it has become focused on her: her bright eyes and cheerful grins and lovely hair, the way she smiles secret smiles just for him when the rest of the squad is not looking, the sound of his name in her voice and the things she has to say, about the Scouting Legion, about her family, about everything, and he cannot help but listen.
It is no longer just physical; somehow his heart has gotten involved, and it would be foolish to fall in love, and Levi is no fool.
But just like a fool, he fell hard.