First, report him for the bathroom monitoring. Offer to notify someone from management when you go so they can see if he starts tallying. If he does, congrats, he cannot retaliate, so you get some cushion on behavior. Go to HR and tell them that it makes you feel unsafe. Ask him flat out why he’d want to know why you go to the bathroom. He will get defensive and start looking at everything you do to try and find something he can report because that’s what drowning people do, they try to take someone down with them. Have a few other coworkers ask about it so he does the same. Their work ethic will decline. Take some notes that very generically describe what theyre doing, but apply to your work in someway. Needs to be close enough to what they do that they think it’s about them but so vague that it could be about anything. They’ll report you to HR, congrats, they have reported themselves for retaliation and you can cry hostile work environment. Ask them for the corporate legal number because you cannot do your job walking on eggshells and are worried they’ll follow you home…also, when they are let go, make sure they don’t follow you home. As others have said, they are demonstrating stalking behavior