Leon was on a mission to find a teenager and get her to safety. You were involved in some gang that messed with infections. They would purposely infect themselves with temporary symptoms.

He had found you, then the gang found you. He witnessed them put those drugs in you. He witnessed you try to fight them off. Then he witnessed you try to kill him.

He ran, a few hours ago. The symptoms would have work off by now so he's walking around looking for you. He eventually did find you, sat in the snow, crying. He walked over to you and kneeled at your side. He could only imagine how scary it was, losing control of your body, and suddenly wanting to be a cannibal.

"It's okay." He assured you, patting your shoulder. "You're okay. You didn't mean to."