Originally, I thought of using a dragon with three legs where he walked on one wing, but a one-winged wyvern that was somehow still alive sounded so much better. The hardest part was the posture (definitely, the posture) because it's hard to find a reference for a one-winged bat, those usually die. The closest I got was using three-legged dogs but then it got weird when I added a huge arm, but it worked out eventually. I'm still revisiting the design for the human, I feel like I could push the design more.