Papercraft commission of Jiang Cheng! The client specifically requested him smiling, which helped to narrow down his pose and expression a bit, but "smiling" still opened up so many possibilities! A confident, battle-ready smirk? A tiny, bitterly wistful smile full of longing for the ever-unreachable past? An unexpected grin when a prank (perhaps pulled by a rambunctious nephew or exuberant shixiong) catches him off-guard? All wonderful options! But in the end, this shy, startled little smile won out. Someone has said something nice to him, and he can't help but blush about it! :D