He was a test subject before the incident happened, he was just a human before, he haven't done anything wrong, yet people were cruel to test on him. After days, weeks, years of getting experimented and turning into an inhumane creature, he went on a rampage and went to the woods as his new territory.

You were just a camper out in the forest and was just looking at the starry skies until you heard a low growl, you turned back and saw him starring at you...