Plot twist Erwin's ass got flat because he spent so much time sitting on chair-kun. It's chair-kun's fault and that's why Levi purposefully tips it over before confronting the War hammer titan.
I need a second to compose myself because did Chair-kun just meet Flatasswin?
This.Is. The.Greatest.Day.Ever.
So we know the chair in Marley can’t be Erwin’s actual chair. However, the tossed chair could indicate Levi’s deep seated resentment towards chairs in general. Perhaps all hard chairs are symbolic to Levi of the evils done to Erwin’s ass. Tossing chair-kun may be a coping method for dealing with his profound guilt, sadness and regret. I’ll bet that in the long years waiting to seek vengeance on the Beast Titan, Levi took out some of his anger by tossing chairs.
We could expand this theory to infer that this is why Levi sleeps in a chair. Perhaps he is subconsciously trying to protect Erwin from the chair. Or maybe Levi sleeps in a soft chair in a subtle effort to show Erwin that there was an alternative.
Either way, Levi likely sees Erwin’s flat ass as a failure on his part. Erwin spent too much time in a chair and Levi couldn’t stop him. Levi couldn’t save Erwin from the chair. If so, the tossed chair in chapter 102 makes a lot of sense. Isayama positioning the chair just below Levi is a symbol of regret in what should be Levi’s purely majestic reappearance.
