What is like to be seen by you.
Something so personal about LeviHan to me is their conception of being seen. What clicks in Levi once he meets Hange is that they reach out in a curious way, is kind and treats him well, despite how he's introduced. Hange sees him. and that's what leads to their bond.
Hange is the only person Levi can be himself with. Hange doesn't see him as the strongest soldier, or a criminal, or a burden. Levi is just Levi. Even if in the beginning he tries to push them away, that copy mechanism fails cause Hange watches; they're observant, they are a scientist and knows human behavior. Levi understands Hange sees right through him (not in a very intimate way at first, ofc) and that's what makes him finally give in. Their rough acid interactions little by little turn into a secret code.
Once Levi knows Hange sees him— after being despised, mistreated and used as a tool, he can finally rest. There's no facade and he's no longer the SC captain. He's just a man with a huge love for fancy tea, a clean freak that under Hange's sight won't be judged.
Eventually, Levi starts speaking more a more. At first it's just questions about Hange's day, but then it's a venting of his own. Hange watches him. He's very talkative, he's funny in a hilarious way and then both find out raw and outrageous humor is their thing.
In a room they don't need words, one glance is enough and sometimes Levi thinks they have a thelepathic connection. There's no place and time to meet, they just know where to get. In silence, drinking tea, talking shit, comfort place is where the other is as well.
Levi finds in Hange's eyes a light where he is seen as the person in the very late night, silent, with no obligations. He knows he doesn't even have to pretend or to suppress parts of him; his traits and emotions. That's why he stayed by Hange's side, because even under the sunlight, in front of cadets and commanders, Captain Levi can still be just Levi. Being watched is not only making proud your comrades, for Levi and Hange watching and being seen is an act of love, to know the other.