I think you should be asking your supervisor and the doctor for advice. Perhaps a team conference is in order. Have you read the kid's history? Sounds borderline.
Personally, I'd be doing spiritual warfare for this. That is, I'd be taking the authority I have as a Christian and commanding the demonic spirits to leave this person and the whole area. I'd be annointing the place with oil, sealing the devil out, covering the place with the blood of Jesus. I'd do it very quietly, very secretly, so as not to call any unnecessary attention to myself but I'd be doing it. I'd be commanding the spirit of fear and the spirit of intimidation to be still, yet I'd be wary. If you're not a Christian, skip this part. No offense is meant to anyone, this is just how I, as a Christian, would be using the authority I have as a Christian to take charge of my scary, unsafe work world. And, having done the battle, I'd spend lots of time praising God. Station your angels round about you to keep you safe, too. And know your escape routes.
You are right to not let it be known that you are scared, I think, although on more than 1 occasion, I have said to patients that "when you act that way, it is scary." They have looked at me increduously. The scary stuff diminished. IT was as if they felt trapped but could now accept permission to behave better.
Do you guys have activities for the residents? Board games, movies, crafts, exercise, cards? What do they do all day? If your aides are not interacting with them but are instead sitting at the nurses' station, start assigning them to interact with the residents out in the Activity Room. Try talking about baseball or whatever with this particular one. What are his interests?
I wish you well.
The following member says Thank You: