Tell Nengo this: Levi and Petra actually did have moments together, those being subtle. In the official game (Isayama authorizes it, so it is official), Levi saw Petra baking sweets and cooking food, and since Levi didn't know how to cook or bake (the underground, probably, from being homeless), he was eager for Petra to teach him. Also, I saw the interview of Levi's voice actor, he likes Petra, and it is hinted that he ships them both, too. Don't forget about the cart scene, death scene, etc.!
WHOA! Sorry Anon, it took MONTHS to answer this, Tumblr never notified me. Well I shared your thoughts with Nengo and this is what she had to say.
(Note: She is talking to me, so it is very casual about her thoughts on this.)
Sorry to say we never knew about that little fact, and we really try not to get too into the details.