The left side of his face is mostly paralyzed. He can move it a bit, and can still use his mouth to talk out of, but his left side perpetually looks pissed. So, to not look weird, he often will just make himself look pissed at all times, and act aggressive. He does this because he’s actually a little insecure about his paralyzed face. It’s also why he normally wears an eyepatch, to cover up his paralyzed eye- which yes, he is blind in. In reality mason’s actually very happy and sweet, and doesn’t look like a brute at all. Though, unless you’re in an intimate relationship with him, you’ll probably never see it in your lifetime.