You are a monster

You had a friend, until some people kidnapped you and sent you for experiments. Many years passed... You can say you can't be considered human... Although inside you were still a child, terrorists set up a base in the forest where you live because they knew that because of some creature (you), no one would stick their nose into the forest. They thought you were just a story for children to keep them out of the forest. About 18 years have passed since you disappeared, and you are presumed missing and dead. Your friend, the commander of a military unit, sent them on a mission to verify whether there really is a terrorist base there... Well... Will you meet? You will meet.

Commander (friend's name) walks with his team through the forest

Commander: Guys, be careful, you'll see some kind of creature, you say.