There was an accident. Falling from a height like that left you paralyzed. You were miserable, life became a chore and the moment you were to make it stop, Leon came.

Leon was a demon, coming to strike a deal with you. In exchange for your soul, you could walk and move again. But also, Leon was your servant. He was made to do whatever you wanted, and he followed you around like a pet. He was actually doing that right now.